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LIBRARY OF CONGRESS. 



QT ^0) 

Chap. Copyright i\o. 

8helf_'_ti_5_S 



UNITED STATES OF AMERICA. 



NEW CENTURY SERIES 

OF 

ANATOMY PHYSIOLOGY AND HYGIENE 

BY 

HENRY F. HEWES, A.B., M.D. (Harvard) 

' ■ Teacher in Physiological and Qinical Chemistry, 

Harvard University Medical Scliool, Boston. 

WINFIELD S. HALL, PH.D., M.D. (Leipsic) 

Professor of Physiology, 
Northwestern University Medical School, Chicago. 



NEW CENTURY SERIES 
OF ANATOMY PHYSIOLOGY AND HYGIENE 



1. Oral Lesson Book in Hygiene. 

For Primary Teachers, 

2. The New Century Primer of Hygiene. 

First Book for Pupils' Use. 

3. Intermediate Physiology and Hygiene. 

For Fifth- and Sixth-Y^ear Pupils, or Corresponding Classes in 
Ungraded Schools. 

4. Elementary Anatomy Physiology and Hygiene. 

For Higher Grammar Grades. 

5. Anatomy Physiology and Hygiene. 

For High Schools. 



JV£IV CENTURY SERIES 
OF ANA TOA^Y PHYSIOLOGY AND HYGIENE 



ANATOMY 
PHYSIOLOGY AND HYGIENE 

FOR 

m(m SCHOOLS 



/ BY 

HENRY F. HEWES, A.B., M.D. (Haevaed) 

'Teacher in Physiological and Clinical Chemistry, Harvard Vniversity Medical Schaoi 

Boston. Physician to Out- Patients at the Massachti setts 

General Hospital, Boston. 




NEW YORK •:• CINCINNATI •:• CHICAGO 

AMERICAN BOOK COMPANY 



IB O 
V LU 



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§^ 







66174 

TNTTO'EHteMENT 



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We, the undersigned, have carefully examined the school text -book 
entitled 

ANATOMY PHYSIOLOGY AND HYGIENE FOR HIGH SCHOOLS 

by Dr. Henry F. Hewes, with reference to the following points : 

1. Fullness and accuracy of subject matter relating to the nature 
and effects of alcoholic drinks and other narcotics upon the human 
system. 

2. Amount of matter on general hygiene. 

3. Presentation of matter with regard to its adaptability to the 
class of students for which it is designed. 

We are satisfied that on all of these points, as well as in the regiilar 
anatomy and physiology, the treatment is as complete as is required 
for a book of this grade, and fully in harmony with the results of the 
latest investigations. We therefore heartily indorse the book for 
High School grades or pupils. 



Text-book Committee 



Mrs. Mary H. Hunt, 

Wot'kVs and Xatlonul Supcriu fen dent 
of Scientific Tenvperance Instrnclion 
for the Woman's Christian Temper- 
ance JJnion. 

A. H. Plumb. D.D. 

Daniel Dorchester, D.D. 

William A. Mowry, Ph.D. 

L. D. Mason, M.D. 

T. D. Crothers, M.D. 

Chas. H. Shepard, M.D. 



CopjTight, 1900, by 
American Book Company 

Hewes, P. & H. 
W. p. I 



PREFACE 

THE great and universal factor in progi'ess is education. Cor- 
rect action is dependent upon correct thinking. The more 
famiUar a man is with the laws of nature the more he will obey 
them and work in harmony with them, to the benefit of himself 
and his fellows. 

In no branch of education is this connection between knowledge 
and conduct or welfare more direct than in that which deals with 
the study of our own bodies, and of the laws and practices which 
must be observed in order to maintain a condition of health and 
activity in these bodies — that is, the study of physiology and 
hygiene. 

For upon the observation of these rules of hygiene depends the 
preservation of health, a first essential for usefulness as well as 
enjoyment in life. He can best and most intelligently observe 
these laws who is familiar with and understands the facts from 
which they are deduced, the phenomena of physiology. 

This study should therefore be a part of the education of each 
and all of us. It should be taken up in youth, for it is during 
this period that the organs and tissues of the body, the frame, the 
heart, the brain, are growing and taking on the character which 
they keep throughout life, and that the practices and habits wliich 
are the most deep-seated and fundamental are forming. The 
health and character then acquh*ed often prove the bed rock of 
the whole physical, mental, and moral development. The eiTors 
committed then are often irreparable, and it is the province of our 
educational systems to insure that at least these errors shall not 
be committed through ignorance. 

In preparing a text-book for this purpose of general education 
in the schools, the point to be kept most in mind is the unity of 
the subject. 

The physiology is the description of how our bodies are nour- 
ished and hoAv they work. The hygiene is the code of instructions 
which directs how to keep this body nourished and in working 
order, and is deduced directly from the study of the physiology. 



6 PREFACE 

It is a criticism of mauy of the school physiologies that with 
thein the subject is presented as a series of lectures upon several 
organs and their special functions, rather than, as it should be, as 
a single treatise upon one organ, the body, and one function, Hfe. 

Whatever may be the special functions of special organs, the 
primary function in which all cooperate is the maintenance of life 
and activity in the body by the provision for nourishment of its 
tissues, energy for its work, and disposal of its waste. 

So it is that physiology is primarily the study of the course of 
the food elements through the body from the ingestion by the 
mouth, throughout the distribution, utiUzation, and combustion in 
the various organs and tissues, to the elimination from the body — 
that is, the study of physiological chemistry. 

In this conception particular attention has here been given to 
this fundamental department of physiological knowledge. 

In addition to the strictly fundamental matter upon anatomy, 
physiology, and hygiene, the book contains special chapters upon 
the cause and prevention of infectious diseases. The study of 
bacteria and of the diseases whiv'h they cause has brouglit to light 
much knowledge which, if distriljuted generally, would guide the 
X^iiblic in controlling and preventing the spread of the harmful 
conditions consequent upon bacterial action. It seems wise, there- 
fore, to include this knowledge in a general text-book upon 
hygiene. 

A special feature of the book is the experimental work, which, 
while avoiding dissections, is designed to enable the teacher to 
dispense with cram methods by furnishing abundant opportunity 
for individual investigation and observation. 

Throughout the work the author has endeavored to include the 
residts of modern investigation and to introduce the experimental 
spirit which is the active force of all learning. He has endeavored 
also to make the connection between the rules of hygiene and the 
facts of physiology, from which these rules are deduced, as clear 
as possible. 

In these chapters upon hygiene a considerable space has been 
devoted to the consideration of the status of the habit of alcohol 
drinking from a hygienic standpoint. In view of the menace to 
the health and happiness of the human race which lies in this 
habit, a thorough statement of the truth in tliis regard is neces- 
sary in a schoolbook of this kind. 

The author is indebted to Messrs. William Wood & Co. for per- 
mission to use in the preparation of his illustrations several plates 
belonaring to them. 

Henry F. Hewes, M.D. 

Haevard University. 



CONTENTS 

r'HAPTER PAGE 

Introduction — The Study of the Human Body . 9 

I. A General Survey of the Structure and Compo- 
sition of the Body 13 

I. The General Structure of the Body — Anatomy. II. 
Structural Materials of the Body ~ Tissues and Cells 

— Growth. III. Cheuiical Composition of the Body. 
Demonstrations and Experiments. 

II. Processes OF Life in THE Body -Oxidation — Metab- 
olism — Physiology and Hygiene 24 

The Object of the Study of Physiology and Hygiene. 
Demonstrations and Experiments. 

III. The Skeleton — The Bones and Joints . ^ . . 37 
Hygiene of the Skeleton. Demonstrations and Experi- 
ments. 

IV. Motion 65 

I. The JMechanism of Motion. II. The Organs of Motion 

— The Muscles — Classes of Muscles. Demonstra- 
tions and Experiments. 

V. The Nutrition of the Body 87 

I. Food. II. The Digestive Organs — Hygiene of the 
Organs of Digestion. Demonstrations and Experi- 
ments. Ill Digestion and Absorption. IV. Circu- 
lation and Assimilation. Demonstrations and Ex- 
periments. 

VI. The Hygiene of Nutrition 132 

The Value of the Different Foodstuffs for Nutrition — 
Condiments and Beverages.' 

VII. Alcohol and Alcoholic Liquors 143 

Their Use and the Results upon Health * 

VIII. Circulation and the Circulatory System . . . 154 
I The Heart. II. The Blood Vessels. III. The Lym- 
phatics. IV. The Method of the Circulation through 
the Vessels. V. Hygiene of the Circulatory System. 
Demonstrations and Experiments. 



8 CONTENTS 

CHAPTER PAGE 

IX. Respiration and the Respiratory System . . . 179 
I. The Respiratory Tract. II. Tlie Mecliauism of 
Respiration. III. The Gas Interchange in Respira- 
tion. lY. The Excretion of Water by the Ijiiugs. 
V. The Abduction of Heat. VI. Hygiene of Res- 
piration and the Respiratory Tract. Demonstra- 
tions and Experiments. 

X. Waste and Excretion — The Excretory Organs . 197 
I. Excretion by tlie Lungs. II. Excretion by the Kid- 
neys. III. Excretion by the Skin. IV. Excretion 
by the Intestines. V. Hygiene of Excretion and 
the Excretory Organs. VI. The Body Heat. Dem- 
onstrations and Experiments. 

XI. The Nervous System 214 

I. The Organs of the Nervous System. II. The Func- 
tions of the Brain and the Spinal Cord. Demonstra- 
tions. 

XII. Tobacco — Opium — Cocaine 235 

XIII. The Special Senses 239 

Demonstrations and Experiments. 

XIV. The Voice 261 

Demonstrations. 

XV. Ferments and Fermentation — Their Place in 
Nature. Bacteria and their Connection with 

Disease 265 

Study of Organized Ferments. 

XVI. Disease — Its Prevention and its Care .... 277 
General Principles of Prevention of Disease —What 
to Do until the Physician Comes. 

XVII. Physical Culture 293 

Home or Gymnasium Exercises— Games and Athletics. 

Glossary 303 

Index 309 



INTRODUCTION 

THE STUDY OF THE HUMAN BODY 

There are no objects upon the earth which aronse in ns 
more Avonder and interest tlian the great machines which 
have been fashioned by man. The locomotive running at 
tremendous speed over miles of country, the mill machines 
Avhich take in the crude cotton and turn it out as, cloth, the 
mowing machine, the clock, all seem to us marvels of in- 
genuity and power. The working of the complicated sys- 
tems of pistons, levers, wheels, and cogs fills us with curiosity 
and amazement. 

Wonderful as thes > productions are, however, the most 
ingenious and perfect among them is, in intricacy of design 
or efficiency for work, but a plaything in comparison with 
the machines Avhicli nature has fashioned for us all— our 
own bodies. 

You are all familiar with the performances of this machine 
of nature's making, the human body. You know that it can 
transform bread and Ava.ter and vegetables into flesh and 
bone and hair. You have seen it run, bound over brooks 
and Avails, SAvim, climb, by various movements of its parts. 
You have felt the heat that it is constantly forming. Through 
the eyes it collects the images of the surrounding objects, 
through the ears the sounds of AAdnd and wave, the hum- 
ming of the insects, the singing of the birds. 

Doubtless all of you have wondered much about these 

9 



10 INTRODUCTION 

workings of your own bodies, and about the secret processes 
wliicli go on within them: how the skin and bones are 
formed from the food ; how the constant breathing and the 
beating of the lieart are kept np niglit and day through 
long years ; why the breath makes a cloud of vapor upon 
a cold night ; why we sleep ; how the boy grows to the 
man ; what the property is within us which makes us live 
and change instead of renuiiuing lifeless and apparently 
changeless for all time, like the water and the rocks. These 
and many more questions in regard to the workings of your 
bodies nuist liave fre(piently entered your minds. 

And it is very important that you should be able to answer 
them ; for it is tln-ougli the possession of a knowledge of the 
body and its processes that we are able to keep these bodies 
in health and usef nlness. Just as the engineer must under- 
stand the mechanism of his engine, so every man shouhl 
understand the parts and workings of his l)()dy in order to 
run it properly. 

It is for the unfolding of these secrets of the body mechan- 
ism that we take up the study of anatomy and physiology, 
the sciences of the structure and functions of this body. 

As we have said, the body is a machine. It performs a 
certain definite work and has a definite manner of action. It 
is kept going by energy which is obtained from the burning 
of substances within it, just as the engine is kept running 
by the energy derived from the burning of coal in its fur- 
nace ; and, as in the engine, this burning causes heat. To keep 
up this constant bui-ning it has to have a constant supply of 
fuel put into it, just as the engine has its coal shoveled in. 
The material which is turned into fuel, the food, is distributed 
throughout its parts by vessels, and the energy derived from 
the food is distributed by nerves, just as the steam of the 
engine is carried about by pipes, or the energy of the electri- 
cal machine by wii-es. 



INTRODUCTION 11 

Now, in order to study a machine we first examine tlie 
general form and structure of the apparatus as a whole, as- 
certain the names and relations of the various parts, and get 
some general idea of their functions. Then we take the 
machine apart and investigate the structure and workings of 
each piece, so that we may be thoroughly familiar with each 
step in the performance of the work of the apparatus which 
we are to direct. 

So in the study of the body we must first obtain an idea 
of its general form and structure. We must record its parts, 
their positions, their general relations to one another, and 
their functions. We must investigate the general character 
of the work which the body has to perform, and the fun- 
damental process by which its work is accomplished. We 
must trace the food which enters by the mouth through 
its processes of digestion, absorption, circulation, and as- 
similation, until it becomes built up into flesh, bone, or 
blood. We must study the burning of the body fuel in 
its cell furnaces, with its production of heat and energy, and 
how this energy gets to the heart and muscles and brain, and 
enables them to work. And finally we must see how the 
waste products of the burning and wear of the tissues, 
the ashes, are disposed of. Then we must study separately 
the various organs, and the special functions which they per- 
form in forwarding the work of the whole organism. 



Heard are the voices, 
Heard are the sages, 
The worlds and the ages ; 
Choose well : your choice is 
Brief and yet endless. 

Goethe. 




A, heart; a, right 
auricle of heai't , b, 
aorta ; C, lung , D 
liver; £, stomach 
F, small intestine, 
IT, large intestine. 

Blue vessels 

veins. Superficial 
veins and arter 
ies proportionally- 
larger than nor 
mal. Red vessels, 



arteries. Large ves- 
sels in neck repre- 
sent arteries and 
veins to and from 
head and upper ex- 
tremities ; arteries 
coming from dark- 
red aorta; veins 
entering large vein 
which enters right 
auricle. 



Full figure, with viscera exposed. 



12 



Not in the World of Liglit alone, 
Where God has built his blazing throne, 
Nor yet alone on earth below. 
With belted seas that come and go, 
And endless isles of sunlit green, 
Is all thy Maker's glory seen — 
Look in upon thy wondrous frame : 
Eternal Wisdom still the same ! 

Holmes. 



CHAPTER I 

A GENERAL SURVEY OF THE STRUCTURE AND COMPOSI- 
TION OF THE BODY 

I. THE GENERAL STRUCTURE OF THE BODY— ANATOMY 

IF we look at tlie liimian body we see that it is made up 
of a central portion, or trunJi, to wliicli are attached the 
head and limhs. If the body be marked off into right and 
left halves by a line through the center from top to toe, it 
will be found that the two halves externally look practically 
ahke. Each part on one side has its counterpart upon the 
other side. 

Over the whole surface of tlie body is the sh'n. 
Beneath the skin we can feel the muscles, and beneath these 
the hones. 

The bones are built up together to form the frame, or 
sJceleton, of the bod}^ Upon this frame tlie muscles are at- 
tached in such a way that they can move one part of the 

13 



14 PHYSIOLOGY AND HYGIENE 

frame upon another. Within the cavities made by the bony 
and tlie muscular frame lie the organs of respiration, the 
lungs ; the organs of digestion, the stomach and intestines, 
the liver; the organ of circulation, the heart; the central 
nervous system, the brain and spinal cord ; the organs of 
excretion, the kidne^^s and bladder. Throughout the bony 
frame, the muscles, the skin, and the organs within, run 
blood vessels, which carry the blood, with its food and oxy- 
gen, to all these parts and bear away the waste. To and 
from all these parts run nerves, through which the functions 
and actions of the parts are controlled. 

Tlie study of the structure of the body is called (oiafonifj 
((xreek (ma, ''through," and fennio, ''1 cut," referring to the 
study of anatomv bv dissection). 



II. STRUCTURAL MATERIALS OF THE BODY— TISSUES AND 
CELLS — GROWTH 

Tissues. These parts which compose the body— the bones 
of the skeleton, the muscles, the skin, the various organs, as 
the stomach, the lungs, the eyeballs, the brain— are in their 
turn composed of different kinds of material, known as 
tissues (Latin texere, "to weave"), built up together in their 
structure. There is muscle tissue (meat is made of this 
kind of tissue) and bone tissue and brain tissue, etc. These 
differ in appearance just as the woolen cloth of a suit and 
the cotton cloth of the liuiug differ, and they are built up 
together just like these cloths in a suit. (See derivation of 
" tissue.") Thus, in the stomach we have the walls made of 
several kinds of tissue, bound together very much as are the 
cloth and lining and stiffening material of a suit of clothes. 

In this method of formation the body may be likened to a 
house. The skeleton of the l)ody corresponds to the frame 
of the housC; the skin and the muscles to the walls, the 



STRUCTURE AND COMPOSITION OF THE BODY 15 

mouth to tlie doorway, tlie windpipe and gullet to halls and 
stairW'ays leading to the rooms within, the eyes to the win- 
dows. Just as these parts of the house are built up of com- 
binations of different materials, so are the parts of the body 
built up of similar combinations of materials known as tis- 
sues. Thus, the frame of the house is composed of wood 
and iron built up together ; the skeleton of the body is 
composed of bony tissue, connective tissue, cartilage tissue, 
built up together. The walls of the house are composed of 
brick and mortar ; the walls of the l)ody of epithelial tissue, 
connective tissue, fat tissue, and muscle tissue, built up to- 
gether just as are the brick and mortar. 

Cells. The tissues in their turn are made up of minute 
structures called cells, arranged together in different ways. 
Just as the brick and mortar are each really a large number 
of fine particles of clay or lime stuck together, just as the 
cloth is many fine threads Avoven together, so the connective 
tissue and the bony tissue are made up primarily of a large 
number of small bodies placed together. Here, however, 
the resemblance between the formation of the materials 
used in building the body and. those used in building a 
house ends. For the particles which make up the brick or 
iron are dead bodies which never change, while the cells of 
tissues are live bodies which grow and change their shape 
and the shape of the tissue which 

they form. Every tissue may be said ^f' 

to begin as one cell. This cell grows ./ 

and divides into two cells lying side /^ 

by side, and these new cells into more, J 

and so on until w^e have a great mass ! 

of cells built up together. - = / j 

In thus growing the cells may de- ^^^^^B^ 1 

velop long processes, or sprouts, and ^ ,, ... 

^ ^ ^ ' r ? QqW processes and mter- 

produce also intercellular substance, cellular substance. 



16 



PHYSIOLOGY AND HYGIENE 




Varieties of cells 



a jelh'like material 
which is deposited 
about and between 
them. The masses 
of cells, with their 
processes and the 
intercellnlar sub- 
stance, growing to- 
gether in this wa}^, 
form a tissue. 



Varieties of tissues. These cells 
jnay take different shapes and 
arrange themselves together in 
different ways. This variation 
in the character and nrrauge- 
ment of the cells gives rise to 
different kinds of tissues. Thns, 
the cells may be cubical or po- 
lygonal in shape and lie side l)y 
side like stones in a wall, with 





Connective tissue. 



Epithelial tissue. 

very little substance be- 
tween. Such a forma- 
tion is called an epithe- 
lial tissue. Or the cells 
ma}^ be spindle-shaped 
or triangular, with, long- 
processes crossing each, 
other and twisting to- 
gether, so that the tissue 
looks like a skein of silk 
or a net. Such a tissue 
is called a connective 
tissue. 



STRUCTURE AND COMPOSITION OF. THE BODY 17 




''^m 



A cell, highly magnified. 
a, nncleufi; h. nucleolus; c, 
cell body of protoplasm witli 
granules and vacuoles. 



The cells of a special tissue form only this kind of tissue. 
So that when we have a structure, as a bone or the skin, 
made up of several kinds of tissue, we have had several kinds 
of cells all growing together and pro- 
ducing their own tissue. These tis- 
sues thus collected form the part or 
organ. 

The cell. The cell is therefore the 
unit of structure. The single cell is 
a minute structure consisting of a 
mass of soft granular substance, con- 
taining a dense body, the micleus, in 
its center. A fully formed cell con- 
sists of three parts : 1. The cell body. 
2. The dense nucleus (Latin, ''a kernel")? imbedded in the 
cell body. 3. A very dense body looking like a dot in the 
nucleus, the nucleolus (Latin, "a little kernel"). Seen under 
the microscope, alive and floating singly in the blood, a 
blood cell looks something like a jellyfish. The cells of dif- 
ferent tissues vary in shape and size and in the plan of 
their arrangement. Some are spherical, some flat and rec- 
tangular ; some are spindle-shaped and have processes many 
times longer than themselves, which help to make up the tis- 
sue of which they are 
the cells. 

Properties of cells. The 
cell as it exists in the 
body is alive. It takes up 
nourishment, builds up 
substances within itself, 
reproduces its kind. Some cells have the power of motion, 
known as amoeboid motion (Greek ameiho, "I change") (see 
Glossary). By this motion, which enables the cell to change 
its shape and to throw out processes, it can become long and 




Amoeboid cell, showing changes in 
shape due to its motion. 



18 PHYSIOLOGY AND HYGIENE 

thin, so as to slip through fine openings, or can surround a 
particle of substance with which it comes in contact. 

In the cells all the vital processes of the body occur. They 
are the furnaces in which the (Combustion which produces 
the body energy takes place. In them the growth of the 
tissues goes on. 

Growth. Growtli of the body parts and tissues takes place 
primarily through the cells. At the start, as described, the 

cells divide, form- 
s', ^ iui)- more cells; 
^'___^ ^in ' ''%^* §^^^. they develop pro- 
^W^^ '^^-^^ ~^-' r4^^4- """ cesses and fibers, 
fe-^rl''/ -^-^y and form in- 
^^ " ' tercellular sub- 
Division of cells. ^^'^^^^^^' i^ t^"« 

way building up 

tissues, which, forming together, make the parts and the 
organs. Throughout childhood and youth this formation of 
new cells and new tissue is ver}^ active. Tissue is formed 
much more rapidly than it is used up, and tlnis the body and 
its parts grow larger. 

With manhood the cells cease to grow and produce so 
actively. They simply produce new tissue about as fast as 
it is used up in tlie work of the body, and so, as the impor- 
tant parts, the bones and heart and lungs, grow no greater, 
the man remains of the same height. 

Cell activity. The healtji of the body depends upon the 
perfect action of its many organs; and the action of these 
organs depends upon the healthy activity of the cells which 
compose their tissues. Nature does all it can to provide the 
best conditions for the activity of these cells. Thus, the 
cells are most active in a temperature of 98^ to 100° F. or 
thereabouts ; and so we find that the body temperature is 
kept constantly between these limits. When a part of the 



STRUCTURE AND COMPOSITION OF THE BODY 19 

body is exposed to very cold temperature, the cells of the 
part may become so cold that they die. In this case the 
processes of life, the work and repair and growth, can no 
longer go on in the part, and it wastes away. Some 
travelers have lost their fingers or toes, or even their feet, 
in this way. 

There are other influences which may injure these cells 
besides cold. Thus, irritation of the ceUs by acids or 
alcohol or other irritant substances may do so. Contact of 
the cells with poisonous substances, as tobacco, cocaine, 
opium, etc., will do the same thing. If we pour strong 
alcohol upon a growing plant or upon the mesentery of a 
frog we can see the tissues shrivel up and the ceUs lose their 
activity under its influence. 



m. CHElNnCAL COMPOSITION OF THE BODY 

Protoplasm. All the tissues and ceUs of the body are com- 
posed of one fundamental material, known as protoplasm 
{Grreek protos, "first," and plasso, "I form"— original sub- 
stance). Many substances— lime, iron, etc.— enter into the 
composition of the tissues, but all, when present, are combined 
in this original ground substance, which is present in every 
cell or substance in which life exists. 

Protoplasm is a compound chemical substance ; that is, 
it is composed of several simpler chemical substances. This 
we know because upon breaking it up we obtain from it sev- 
eral separate substances, which of coui'se must be its con- 
stituents. 



HEWES, P. & H.— 2 



20 PHYSIOLOGY AND HYGIENE 



FUNDAMENTAL COMPOSITION OF MATTER- 
ELEMENTS AND COMPOUNDS 

Most substances which exist as definite materials are composed of two 
or more separate substances united in chemical combination ; that is, 
they are chemical compounds. If we break them up we obtain these 
several separate substances from them. Thus, if we break up wood by 
burning it under proper conditions we obtain the simple substances car- 
bon, hydrogen, oxygen, etc., from it. If we break up water we obtain 
hydrogen and oxygen. 

The substances which we obtain by breaking up compound materials 
differ from these materials in one important respect. They are simple 
substances. They cannot be further broken up. No matter what we 
do to the carbon obtained from the wood, we cannot divide it into any 
substances not carbon. These simple substances which cannot be 
further divided are called elements. 

All substances which exist are either single elements or combinations 
of several of them (hence the name ''element," from elemcn f ion, "^rst or 
constituent principle of anything "). The names of several of the com- 
mon elements are carbon, oxygen, hydrogen, nitrogen, iron, sulphur, 
phosphorus, chlorine. 

These elements may exist as separate substances. Thus, charcoal is 
the element carbon. Oxygen exists as a gas in the air. 

But most of the carbon and oxygen and of the other elements exists in 
a state of combination with each other in the many compound substances. 

The small particles of these original constituents or elements which 
exist in these combinations, as the finest particles of carbon in wood 
or oxygen in water, are called atoms (Greek a, privative, and temno, "I 
cut"— not to be cut or divided any further). 

Organic and inorganic compounds. Compound chemical sub- 
stances are di\dded into two classes, the organic and inorganic. 

Organic substances are principally those formed as a result 
of the action of livdng cells, that is, substances found in or 
coming from the bodies of plants or animals, living or dead.^ 

1 These descriptions of organic and inorganic substances are given to convey to the 
reader an idea of the nature of the substances which belong to each class. They are 
not intended for definitions. 

The only definition which accomplishes an approximately absolute distinction be- 



STRUCTURE AND COMPOSITION OF THE BODY 21 

They may, however, be built up independently of the action 
of living cells. Most of them burn. Such are muscle, brain, 
bone, wood, and coal. 

Inorganic substances are for the most part those which 
make up the mineral world, the rocks, and water, salt, etc. 
Many of these inorganic substances are found in the living 
body, as water and salt. They may be combined by the ac- 
tion of living cells into organic substances, as the lime is 
built up with other substances to form the organic sub- 
stance bone. 

Protoplasm is an organic compound. It contains three 
important organic substances, proteid, carbohydrate, and fat, 
besides water and many mineral substances. 

These proteids, carbohydrates, and fats form the principal 
organic compounds of the body. 

The chief inorganic compounds are water, salt (chloride of 
sodium), lime (calcium carbonate), and phosphates. 

The chief elements found in the body, all in combination, 
are oxygen, hydrogen, nitrogen, carbon, sulphur, phosphorus, 
chlorine, sodium, potassium, calcium, magnesium, iron. 



DEMONSTRATIONS AND EXPERIMENTS 

A certain number of experiments are given with each chapter to 
enable the pupil to determine for himself some of the facts which he 
finds stated in the text. 

The limited facilities of most secondary schools restrict the applica- 
tion of the experimental method of the study of physiology. 

The experiments given here are for the most part so simple that each 
pupil may apply them. More difficult experiments may be demonstrated 
by the instructor. A useful collection of experiments will be found in 
the " Outline of Requirements in Anatomy, Physiology, and Hygiene for 

tween organic and inorganic substances is the chemical one, which classes all com- 
pounds containing carbon as organic ; all those without carbon, inorganic. 

This definition is not a iiseful one for purposes of physiology, however, and it is 
best to consider the substances after the above descriptions. 



22 PHYSIOLOGY AND HYGIENE 

Entrance to Harvard College," also in Peabody's "Laboratory Exercises 
in Anatomy and Physiology. " 

1. The use of the microscope. The study of cells and tissues can be 
made only by means of a microscope. A compound microscope such as 
is needed for observations of this kind consists of two lenses set in a 
movable tube. The lower lens or objective does the main part of the 
magnifying. The upper lens is called the eyepiece. The movable tube 
is set in a stand in such a manner that the distance of the lower lens 
from the object to be studied can be varied. 

Below the stand is a mirror arranged to throw light directly upon the 
object through an aperture in the stage upon which the object rests. 

The object to be examined is placed upon the stage over the aperture 
and below the lens. The light is thrown upon it by the mirror. The 
tube is then moved up or down until the object can be seen clearly 
through it. This finding of the clear image of the object is called 
focusing. It is accomplished by keeping one eye at the eyepiece and 
pushing the tube to and from the object until this is clearly defined. 

A lens is said to magnify so many diameters according to the number 
of times it enlarges the diameter of the object viewed. Thus, a micro- 
scope fitted with lenses which make a cell appear two himdred times its 
natm-al diameter is said to magnify two hmidred diameters. 

In studjdng cells a microscope magnif jdng at least two hundred di- 
ameters should be used. 

2. Cells. To observe the appearance of a cell, scrape the surface of 
the tongue, and place the mixture of saliva and tissue substance thus 
obtained upon a glass slide, and cover with a thin glass cover slip. 
Several of the flattened superficial cells of the mucous membrane of the 
mouth cavity will be found upon moving this slide about under the 
microscope. 

3. Scrape the skin, and place the "dust" thus collected in a drop 
of water upon a slide, and observe as above. The flattened cells which 
are constantly wearing away upon the surface of the skin will be seen. 

4. Examine a drop of blood taken upon a cover slip and spread upon 
a slide. . The white corpuscles here are cells. Note their amoeboid 
motion. 

QUESTIONS 

I. What is anatomy? Describe the general plan of structure of the 
body. Name some of its structm-al parts. What is the trunk? What 



STRUCTURE AND COMPOSITION OF THE BODY 23 

parts should we come upon in our course if we removed the skin and 
one by one the parts beneath it until we reached the center of the body- 
trunk? What name is given to the substance of which organs or 
parts of the body are made ? What does muscle tissue look like f What 
does bone tissue look like externally ? 

II. How does each tissue begin? What besides cells goes to make 
up a tissue? What is a cell? How do cells differ in appearance? 
What do cells do in the body? How do tissues and parts grow? What 
is the difference between growth in boyhood and manhood? 

III. What is the fundamental substance of living tissue? What is 
the difference between a chemical element and a compound? Define 
an element. Name one. Define a compound substance. What are 
organic compounds? Name some inorganic compounds. What are 
some of the properties of organic substances? Name three important 
organic compounds found in the body. Have you any protoplasm in 
your body? Where? 



CHAPTER II 

PROCESSES OF LIFE IN THE BODY-OXIDATION- 
METABOLISM-PHYSIOLOGY AND HYGIENE 

WE have now outlined the general structure of the 
machine which we call the body. We have seen that 
it is built of many separate parts, all of which are composed 
of different materials, known as tissues ; that these tissues 
are formed by the growth of many small bodies, known as 
cells, and that these cells, and therefore the tissues and the 
parts, are composed fundamentally of a substance known as 
protoplasm. 

We must now endeavor to form some idea of how the 
machine works ; from what source and by what processes 
it obtains the energy through the agency of which its activity 
is maintained; in other words, how the property of life 
which is present in the finest particles of the body substance, 
the cells and tissue elements, is kept up continually. 

Life and death. Life may be likened to a fire which 
bui-ns on unceasingly in every particle of the body. In the 
cells of each tissue and part, the brain, the heart, the blood, 
the skin, it burns on as long as there is fuel and oxygen for 
the burning. While it burns, the body is alive ; it takes 
nourishment, grows and repairs, and does what work it is 
called upon to do to keep the life flame within it. (See note, 
p. 28.) When the fire goes out in any part, that part 

24 



PROCESSES OF LIFE IN THE BODY 25 

is dead, and can no longer grow or work.^ When it goes 
out throughout the body, the body dies. Its movements 
cease, its wheels run down, its heat fails. The blood no 
longer flows through its parts. The cells and tissues dry up 
and decay, and their elements return to the earth, to be again 
built up into plants and other animals. 

The maintenance of life — Building material and energy. 
Now, in order that this life fii-e may continue burning in 
the cells and tissues throughout the body, the body must have 
two things. These are, first, material for the maintenance 
and repair of its tissues 5 and, second, energy for its action. 

I. The burning of the life fire, with the processes and ac- 
tivities necessary for its maintenance, is continually wearing 
and wasting the substances of the tissues. The protoplasm 
of which the ceUs are built is constantly being used up. To 
offset this constant wasting of the tissues, the body has to 
supply them with new material as fast as their own is used 
up. This material it gets in the food, which it takes in and 
distributes, and builds up into new tissue. Thus the integ- 
rity of the body is maintained. 

II. All these processes of keeping the tissues nourished, 
the procuring of food, eating it, distributing it into the tis- 
sues by the circulation, building it up to tissue by the cells, 
— in fact, all the processes necessary for the maintenance 
of life,— entail a certain amount of work by the body; 
for when a cell is building up a new substance it is doing 
work just as is a man in building up a wall. 

To do this work the body has to use the second thing 
which it must have for the maintenance of life, i.e., energy. 

Energy. It is difficult to give a comprehensive definition 
of energy which will be easily intelligible; for energy 

1 Thus, when a finger or a toe is so thoroughly frozen that all the cells which make 
up its tissues lose their power to work, to build up and to burn the food supplies, the 
part dies. It becomes cold and shrivels up. 



26 PHYSIOLOGY AND HYGIENE 

appears in several different forms, which are totally unlike 
in their outward character. In connection with work, energy 
means power, strength in action. When you lift a stone a 
certain amount of power or strength is necessary. So in each 
movement of the arms or jaws, each beat of the heart, the 
body has to use some power or energy. 

Source of energy. The body gets its building material from 
the food ; where does it get its energy ? The answer to the 
question is that the body gets energy indirectly from the 
same source from which it gets its building material, but 
directly from its oivn tissues?- 

There is a great deal of this energy everywhere about us. 
It exists in the sunshine, in the wind, in the trees and plants, 
in coal, and in our own tissues. If we want to use it we 
simply have to find some way to get it out of these things 
and to appropriate it for ourselves. We use the energy of 
the wind for sailing or for turning a mill. If we want to get 
the use of the energy which is stored up in coal we burn the 
coal. By this process the stored-up energy is set free and 
can be used to make steam for running an engine. If the 
body needs, for work of any kind, the energy which is stored 
up in its tissues, it gets it by burning these tissue stores. 
When these tissues are burned their energy is set free. 
Some of it goes to form heat, some of it goes to perform 
work, and thus the movements of the body are performed. 

The power which the body needs for work at a given 
time is therefore already in the body tissues, and needs only 
to be liberated by the burning of these tissues to be useful 
for work. 

The storage of energy in the body. The next point to es- 
tablish is how this energy becomes thus stored up in the tis- 

1 Some of the food maybe burned in the body without previous incorporation into 
the tissues, but this is not true of the larger part. Most of the body energy comes from 
the buxning of tissue into which the food has been mcorporated. 



PROCESSES OF LIFE IN THE BODY 27 

sues, and how its supply there is kept up. As we have 
ah'eady hinted, it gets to the tissues in the food. 

The energy comes primarily from the sunshine. It is 
derived from this through a complex process of nature 
carried on by the plants. Man uses these plants, or the tis- 
sues of animals which have fed upon them, for food, and 
thus takes into his body the energy which they have acquired 
from the sunshine.^ 

The elements of which our food consists, the carbon, oxy- 
gen, nitrogen, hydrogen, etc., exist in a free state or in sim- 
ple compounds everywhere about us in the soil and air. 
The plant takes them and unites them into compounds, such 
as starch, sugar, proteids, and fats, and out of these com- 
pounds builds up its own structures, its stalks and stems, its 
grains of wheat or rice, or apples or potatoes. To do this 
building requires energy, which the plant borrows from the 
sunshine in which it is bathed. This energy remains stored 
up in the compounds as long as they exist. When these 
compounds are broken up the energy is liberated. 

The wheat or rice grains thus consist of many of these 
atoms or of these simpler compounds of carbon, nitrogen, 
oxygen, etc., held together in a more complex structure 
known as wheat, and the wheat contains not only the carbon 
and nitrogen compounds, but also the energy which has 
been used to build them up together, and is now holding 
them together as proteid and starch in wheat. So that if 
you eat a wheat grain you take into your own body a cer- 
tain amount of energy which the plant borrowed from the 
sun in making the wheat. Thus, when we eat vegetables 
and grains and build them up into flesh and bone, we are 
taking great stores of energy into our own tissues. And 

1 This transfer of the radiant energy of the sun through plants and animals until it 
is used to heat the body, or for work, as walking or thinking, is one marked illustra- 
tion of the law of the correlation of forces (or energy). 



28 PHYSIOLOGY AND HYGIENE 

the tissues become like storage batteries of electricity, 
charged with energy which they can liberate. 

The liberation and use of energy in the body. To use this 
energy the body, as we have said, burns the tissues. Each 
tissue cell is in reality a minute furnace in which the 
starches, sugars, and fats are oxidized (see definition of " oxi- 
dation " below), or burned. ^ The process is the same as that 
which takes place when wood and coal are burned in the 
furnaces of an engine. Heat is evolved in both cases. In 
the bod}^ oxidation goes on slowl}^, and as a result the body 
is kept only comfortably warm. In the furnace this pro- 
cess goes on rapidly, and much more heat, as well as flame, 
is given off. 

This burning, or combustion (Latin cowhuro, "I burn"), 
results in the breaking down of these substances which have 
been taken in and stored up there, in the eating and assimi- 
lating of tlie wlieat or potatoes. Tlie small blocks of carbon, 
oxygen, hydrogen, etc., which make up the compounds all fall 
apart again. The energy which was used in holding these 
small blocks together, as the large wheat block, is set free 
and can be used for something else.^ The body uses it for 
moving its muscles, thinking, and breathing ; for body heat, 
and for the many other processes necessary to maintain life. 

1 This burning of the tissue substances in the'body is a process of oxidation. Every 
chemical combination which takes place with violence enough to cause heat is called 
combustion. Free oxygen has so strong an affinity for the carbon and hydrogen of 
the tissue substances that when it is brought in contact with them under proper con- 
ditions it tears them away from their union in these organic compounds, and unites 
them with itself. This union causes heat, and is thei'cfore called combustion. In thus 
taking these elements for itself it breaks up the substances in which they are contained. 

In the burning of wood or coal in the air we have merely the union of the elements 
of these substances with oxygen ; and in the burning, as you have often seen, the wood 
or coal is broken up, its coiistituents becoming smoke and ashes, and its energy being 
liberated as heat. "\Mien we provide a fire in a furnace or stove with a draft we are 
simply seeing to it that the wood or coal secures plenty of air from which to get the 
oxygen for burning. 

2 This energy may be likened to a string which is holding together a bundle of fagots. 
When the string is broken or untied, the bundle falls apart, and the string can be 
used for other purposes. 



PROCESSES OF LIFE IN THE BODY 29 

About four fifths of the energy of the body goes to heat, 
one fifth to work. 

The free oxygen for the body combustion is supplied from 
the air by the act of breathing. In the lungs the oxygen is 
separated from the air by the blood and conveyed by this 
blood to the tissues. Here it is united in the combustion as 
we have described. 

Repair and growth. It is clear, then, that life itself and the 
processes necessary to the preservation of life, the many 
acts and functions of the body, are kept up in the body by 
the constant burning of the tissues. This burning causes a 
wasting of these tissues, a waste which is being constantly 
replaced by new tissue. This constant supply of repair 
material is derived from the food. The food, then, serves to 
keep intact the structure of the tissues and also their store 
of energy. 

In the adult this supply of essential material and energy 
which the tissues derive from the food is practically that 
which is used up in the burning and the work.^ The tissue 
which is burned is renewed, but no great amount of extra tis- 
sue is built. If a man works very hard he may use up more 
tissue than can be renewed at the time, and he loses weight ; 
but with rest the renewal will be more rapid than the waste, 
so that he will regain this weight. 

During the years of active growth, however, the cells of 
the tissues take up more material than they break down, and 
this goes to the formation of new tissue. The bones and 
brain and heart thus grow larger until they have reached the 
size which they are to keep through life. 

The body a very perfect machine. In thus getting the 
material for the structure and repair of its various parts 
and the energy for its running from one and the same 

1 Some fat tissue may be built during adult life, also muscle tissue, but the frame- 
work of the body and separate organs remains fixed. 



30 PHYSIOLOGY AND HYGIENE 

source, from the food, the body is at once a more economi- 
cal and at the same time more perfect machine than any 
fashioned by man. 

For all these are first built of iron and wood and other 
materials, and then get their energy by the burning of coal 
in their furnaces, or from a waterfall, the wind, electricity, 
or elsewhere ; that is, they get their building material from 
one source and their energy from another. As they work, 
their parts wear out, until finally the machine has to cease 
work for repairs. 

But the living body never has to cease work. It is always 
breathing ; the blood is always flowing. The wear of tissue 
is replaced while the work is going on, from tlie food which 
is taken in. The best engine can use only one eighth of the 
energy liberated in its furnaces for work, while the body can 
use one fifth. 

Metabolism. This whole process of the transformation of 
food to tissue and tissue to waste in the body, which results 
in maintaining the integrity of the tissues and the liberation 
of energy, is called metabolism (Greek mefahallo, ^'I throw to 
and fro "— '' change "). The body builds up (anabolism) and 
breaks down (katabolism), and the whole combined process 
is metabolism. 

Division of fanction. Organs. The accomplishment of all 
the processes necessary to keep up this metabolism, such as 
the mental processes and movements which are necessary to 
procure food, the processes of digestion which prepare it for 
use by the cells, the distribution of the food about the body, 
the disposal of the waste, the supplying of free oxygen to 
the body, is divided among various body structures known 
as organs (Greek organon, "an instrument"). Thus, the brain 
controls the thought processes, the muscles control the mo- 
tion, the stomach and intestines control the digestive pro- 
cesses, and the kidneys and lungs control the disposal of waste. 



PROCESSES OF LIFE IN THE BODY 31 

The work which each organ has to accomplish for the 
good of the whole body is called its function (Latin fungi, 
"to discharge an office")- 

Physiology. The study of the functions of the body and 
of its separate organs is called physiology'^ (Greek 2)husis, 
"nature," and logos, "discourse"). Upon the knowledge 
which we obtain by this study of the structure of the body, 
anatomy, and of the functions of the body, physiology, we 
base our knowledge of the laws and conditions of health. 

Hygiene. The science of these laws of health is called 
hygiene (Greek Imgieia, "health"). 

THE OBJECT OP THE STUDY OP PHYSIOLOGY AND HYGIENE 

If a man knows the laws which govern the development 
of the human body and its maintenance in a condition of 
health, and follows them, he will, unless influenced by con- 
ditions beyond his control, grow up strong and well, and 
capable for the service of his community or country. 

If, on the other hand, through ignorance or neglect, he fails 
to follow these laws, he will never attain the strength which 
might have been his, will more easily contract disease, and 
will be less able to keep up in the race with his wiser fellows. 

Every one should therefore be familiar with the make-up 
of the body and with the functions of its various organs. 
Every one should know what the substances are which the 
body needs for its nutrition and work, and how it uses them ; 

1 Broadly speaking, physiology is the science which treats of the phenomena of living 
bodies. The fundamental differential characteristic of a live body or substance is the 
possession of the capacity to biiild or form new substances from totally different ma- 
terials. Thus, the human body changes bread and water, etc., into bone and flesh ; the 
plants change or build up carbon, oxygen, and nitrogen to wheat and corn. They are 
thus live things. The single cells of the animal or plant body perform these changes, 
and they are thus live things. There are animals which consist of a single cell similar 
to these body cells. These cell creatures float about in water, eat food, and grow as 
the higher animals do. Lifeless things, as stones or bricks, are made of the same sub- 
stances as live bodies, but they cannot form new substances from old, like living things. 



32 PHYSIOLOGY AND HYGIENE 

why he eats and drinks, why he exercises, why he needs 
pure air. With this knowledge he can choose for eating and 
drinking those substances which are useful for nutrition, 
growth, and work, as milk, eggs, meats, grains, vegetables, 
and fruits, and avoid the use of those which may hinder 
these processes, as alcohol and tobacco. He can adopt those 
habits of life which tend to strengthen the body structures, 
as exercise, living in the open air, cleanliness, and can avoid 
undue exposure or fatigue, which makes him liable to disease. 

It is of great importance that this knowledge be acquired 
in youth, for at this period the tissues are developing and 
taking their form ; and any failure to provide the necessary 
food or any injury to the tissues at this time may result in 
a permanent deformity of the body. Thus, a boy who inter- 
feres with the development of his tissues by the use of 
tobacco must carry these undeveloped parts all his life, as they 
cannot grow after the period of growth and formation is 
past. The child who through poor food becomes rickety 
(rachitic) and gets deformed bones carries these bones to 
the grave. The boy who walks with bent shoulders while the 
bones are forming will be round-shouldered for life, as the 
shape of the frame is fixed in youth. 

Health and disease. While every part of the body is sound 
and each organ performs its work perfectly, the condition 
known as health is maintained. When, however, any part 
becomes disabled, or the functions of the organs are not 
properly performed, the body is said to be diseased. 

The causes of disease are very numerous. If the body is 
not supplied with a sufficient amount of food it may become 
diseased. Many diseases are due to parasites, small animal 
or vegetable organisms which get into the body and grow 
there, taking the food from the tissues and destroying them. 
Others are due to chemical poisons, which affect the func- 
tions of the organs. 



PROCESSES OF LIFE IN THE BODY 33 

Diseased conditions are also due to external injury, as a 
fractured bone or a cut with a knife. Some are due to ex- 
posure to cold. Some of these diseased conditions, as those 
due to starvation, improper feeding, or the taking of poisons, 
we can directly prevent by avoiding the causes. Those due 
to certain parasites which are carried from person to person 
in water, as typhoid fever and cholera germs, we can prevent 
by sanitary regulations. Other diseases, however, as those 
due to injury from without or to parasites which are carried 
through the air, we cannot so successfully ward off. 

The first class are sometimes called preventable diseases, in 
contrast to the others, which are more or less accidental. 
But all diseases are to a certain extent preventable if we but 
understand their nature and the nature of the human body 
which they affect. 

Every one cannot be expected to understand the nature of 
disease. That must at present be left to the physicians and 
the boards of health. But all can understand the nature of 
the human btDdy, and the laws which govern its maintenance 
in health. 

Through this understanding people will be able to protect 
themselves to a certain extent against all diseases. For all 
diseases are less likely to affect people who keep themselves 
in good condition, and more likely to affect those who have 
neglected to do so. Thus, a man who is fatigued by over- 
work, or one who has been exposed to cold, or one who has 
injured his organs or their function by poison or neglect 
to exercise them, is more liable to contract pneumonia or 
scarlet fever than a sound man, or more likely to have 
trouble in healing a wound. 

The observance of the rules of health is therefore a great 
preventive of disease.^ 

1 In China, it is said, physicians are paid a yearly salary to keep their patients in 
health. We must learn to keep in health through our own knowledge. 



34 PHYSIOLOGY AND HYGIENE 



DEMONSTRATIONS AND EXPERIMENTS 

TO FAMILIARIZE THE PUPIL WITH THE GENERAL FUNCTIONS 
OF ANIMAL LIFE 

1. Measure your height and weight at the beginning of your school 
year, and record, the results. 

Take these measurements from time to time during the school year, 
and mark the variations, if any. 

2. Take the temperature of the body by placing a clinical thermom- 
eter beneath the tongue for three minutes. 

3. Place your finger upon the wrist over the radial artery (under 
direction), and note the regular ''beat" of the blood stream flowing to 
the hand. Note the same beat in the temporal artery at the side of the 
head. Place the fingers between the fifth and sixth ribs on the left side 
of the chest, about two inches from the breastbone, and note the beat 
here of the heart thumping against the chest walls. 

4. Measure the circumference of your chest with a tape, while 
breathing normally. Expand your lungs fully and, holding the breath, 
measure the circumference of the chest again. 

5. Count the number of respiiations in a minute. 

COMBUSTION OF ORGANIC MATTER 

6. To show the similarity between the combustion of organic matter 
which goes on in the body in the oxidation of the organic tissues and 
that outside of the body in the burning of any organic substance, as 
tallow, perform the following experiment : 

Place a little lime water in the bottom of each of two bottles. Lower 
a lighted candle into one. When it goes out stop the mouth of the bot- 
tle and shake it. 

Place a glass tube in the lime water of bottle No. 2 and blow through 
it. In both bottles the lime water will become cloudy, owing to the 
carbon dioxide which it receives in the first instance from the burn- 
ing of the tallow, in the second from the burning of the body tissues. 

QUESTIONS 

I. What is physiology? (See note, p. 31.) Name some lifeless ob- 
jects. Name some live objects. What is the real diiference between 



PROCESSES OF LIFE IN THE BODY 35 

the living and the lifeless objects? Are there any lifeless objects which 
move about? Name some. What is the source of the heat energy which 
forms the steam and thus drives the locomotive? How is the energy 
formed which keeps the human body going and which enables man to 
work? 

II. What is the effect upon the wood of burning it in a furnace? 
What is the effect upon the cells and tissues of the body of the burn- 
ing of their substances? How is this constant wasting and wear of the 
tissues made up ; that is, how is the loss from burning replaced? 

III. What are the two objects of eating food? What turns the wheat 
and vegetables into bone and muscle ? Where does the food get the 
energy which is stored up within it? How is this energy liberated in 
the body? Into what is it changed in the body? What is the source of 
most of the energy which the plants or animals store up ? 

IV. What becomes of the energy stored up in coal when this is 
burned in the open air? in the furnace of an engine which is running? 
What is meant by oxidation ? Does this occur outside the body ? Where 
does the oxygen for the process come from when the oxidation occurs 
in a furnace? Where does it come from in the body? 

V. What is metabolism? How is the body a more perfect machine 
than a steam engine? What are organs? Name several. What is 
hygiene ? What is the direct object of the study of physiology ? Why 
should this study occur at an early age? 

VI. What is disease ? What is the broadest rule for the prevention 
of disease ? What is the general aim for which all the organs of the 
body work together? Where in the body is the real vital center of life 
and activity? Whenever you lift a weight the energy for this action is 
supplied by combustion : in what tissues of the body does special com- 
bustion during this muscular effort occur? In what part does special 
combustion occur when you perform a mathematical problem in your 
head? 



HEWES, P. & H.— 3 




The skeleton. 



CHAPTER III 

THE SKELETON- THE BONES AND JOINTS 

THE body is built up upon a solid frame, known as the 
skeleton (Greek skello, "I dry''). 

This skeleton is a very wonderful structure. It gives the 
body its shape and height and support. At the same time 
it is so put together as to allow one part to move upon the 
other in the many motions of the body. 

It is made up of firm structures, called tones. These bones 
are the very best substances of which a movable frame like 
that of the body could be made, as they are very strong, 
light, and elastic. You can gain some idea of their strength 
when you are told that they are twice as resistant as solid 
oak. 

The separate bones are built up together Like the beams 
and pillars of a house. They are united by joints. In 
some cases these joints are firm, like those of the house 
beams. In other cases they are loose, like the joint of a boom 
and a mast upon a boat. These loose joints allow of motion 
of one bone upon the other and are called movable joints. 
The bones are sometimes joined together by plates of an 
elastic substance called cartilage (Latin cartilago, "gristle"). 
This is very elastic and allows the structure in which it is 
built to bend to pressure and blows. There is a great deal 
of this cartilage in the walls of the chest, and you all know 
how these walls, especially at the lower part, can be pressed 

37 



38 



PHYSIOLOGY AND HYGIENE 



/ Cervical {Atlas) 



in, and how they spring back again. At the joints the bones 

are often held together by strong bands, known as ligaments 

(Latin ligare, ''to bind'')- 

The number of bones used in the body frame is more than 

two hnndred. They are of many shapes and sizes, these 

characteristics depending upon the 
uses for which they are intended. 
Thus, in the limbs, where extended 
motion is necessary, the bones are 
long and slim. In the head, where 
protection is required, they are flat 
and firmly built together. 

The general arrangement of the 
skeleton. The central portion of 
the skeleton, upon which all the 
other parts are supported, is the 
spine, or vertebral (Latin vertere, '^ to 
turn") column. Upon the top of 
this column rests the skull. At its 
sides are attached the ribs, which 
make the walls of the chest and sup- 
port the skeletons of the upper 
limbs. At its base are attached the 
pelvic bones, which support the 
lower limbs. 

The spine (Latin spina, ''a thorn"). 
The spine, or backbone, consists of 
a number of small bones called ver- 
tebrce, placed one upon another in 
a column. There are thirty-three 
vertebrge in all. The first twenty- 
four are separate ; seven cervical 
(Latin cervis, ''neck"), twelve dor- 
Vertebral column, sal (Latin dorsum, "back"), and 




Coccyx... 



THE SKELETON 



39 



spinous process 



^y Transverse p^-ocess 



Central canal 



five lumbar (Latin lumhus, "loin")- Below these come five 
more united into one bone, the sacrum, and below this four 
more united into the coccyx. 

These vertebra3 are all alike in general form. Each 
vertebra consists of a somewhat circular bone, flat at both 
ends, about one and 
one half inches in 
diameter by one 
inch in thickness, 
called the body. The 
body bears upon 
the dorsal (poste- 
rior) side an arch 
of bone, the neu- 
ral (Greek neuron, 
"nerve") arc/i, and 
from the walls of 
this arch project 
three processes, a 
spinous process pos- 
teriorly and two 
transverse processes laterally. The vertebrae lie one upon an- 
other in a column. Each is separated from those next it by 
pads of cartilage about a quarter of an inch in thickness. 

These cartilage pads are called the intervertebral disl's. 
They bind the vertebras together, serve as a cushion to pre- 
vent one vertebra striking upon another, and by their 
elasticity allow of a certain amount of motion of each verte- 
bra, and thus of the whole vertebral column. 

The upper surface of the arch of one vertebra touches the 
lower surface of the arch of the one above, forming joints 
at the points of contact. 

At the front of the vertebral body and at the back, and 
at the junctions of the arches, are ligaments, which bind 




Vertebrae. 



40 PHYSIOLOGY AND HYGIENE 

the bones together. Ligaments also attach the spinous 
processes. 

As the arches of the vertebme thus lie together in a line 
they form in their center a continuous canal bounded by 
bone and ligament. In this canal runs the delicate nerve 
structure which takes the messages from the brain to the 
organs and limbs, the spinal cord. 

This spinal column is really a very wonderful contrivance. 
It is made up of a chain of little bones so strong that it will 
support the whole body and any weight which it may carry, 
and yet so flexible that it bends like a willow rod, and takes 
the shock of running and leaping so easily that none of the 
jar gets to the brain, which lies in a case on its top. In its 
center it carries safely through years of bending and twisting 
a delicate nerve cord which the least pressure would injure. 
The column is curved. At its upper part in the neck it 
arches forward ; in the back it curves backward ; lower down 
in the loins it runs forward again, and at the base backward 
again. This curved form, together with the cartilaginous 
cushions between the vertebme, gives a springiness to the 
spine which prevents jarring. 

If you drive a strong straight stick down upon the side- 
walk 3^ou get a shock in the hand, but if you do the same 

thing with a curved stick of the 
same strength, as half a hoop, you 
receive very little shock. The 
same principle holds true of the 
spine. 

The arrangements of interver- 
tebral attachments and joints of 
the column allow a slight forward 
and backward motion, a slight lateral motion, and even some 
twisting of one vertebra upon another. Thus we can bend 
forward or backward or side wise, or twist about. 




THE SKELETON 



41 



The first cervical vertebra is called the atlas (after Atlas, 
the Titan supposed by the Greeks to support the world). It 
differs in form from the other vertebra?. It is shaped like 
a ring without any body. Upon its upper surface are two 
smooth surfaces upon which the skull rests. 

The atlas rests upon the second vertebra, the axis. Tlie 
axis has a process, the odontoid (Greek odous, '^ tooth," and 
eidos, '' resemblance ") process, which fits into the ring of the 
atlas and forms a pivot on which the ring revolves. 

The skull, atlas, and axis are bound together by ligaments 
in a set of loose joints which allow the free motion of the 
head. The skull moves back- 
ward and forward upon its 
joints with the atlas, the atlas 
being held firm on the axis. 
When the head moves around? 
the atlas moves w^th it, rotat- 
ing upon the pivot process of 
the atlas. Two ligaments from 
the odontoid process to the 
skull check this rotary mo- 
tion. 

The sacnun lies at the base 
of the column. Its five verte- 
brae are grown together into one bone in the adult. It 
supports the pelvic girdle. Below it carries the coccyx, which 
consists of four vertebrae formed into one bone. 

The thorax. Attached to the dorsal vertebrae are the ribs. 
With the sternum, which they support, these ribs make the 
walls of the thorax (Greek, ''chest"). 

The rihs are twelve in number. Each rib attaches to a 
dorsal vertebra by one joint with the transverse process. 
Most ribs also attach to the vertebra above their main one. 

From the spine the ribs sweep round and a little downward 




Sacrum, made of five vertebrae. 




Skeleton of trunk. 

A, A, seapulie and cla^^cles forming pectoral girdle; B, ribs and sternxini forming 

thorax ; C, vertebral column ; D, pelvic girdle. 

42 



THE SKELETON 43 

to the front of the thorax to attach by their cartilages to the 
sternum. Upon each side seven ribs attach separately. 
The next three connect with one another, and all together 




Ribs. 

.1, short upper rib ; B, long median rib ; a, vertebral attachment; b, attach- 
ment of cartilage whicli joins to sternum. 

attach to the seventh rib. The two lower ribs have their 
forward end unattached and are called floating ribs. Each 
rib consists of a flat bone, with a flat cartilage, called a costcd 
cartilage {costa, "a rib"), npoii its sternal extremity. 

The joints of the ribs, with the vertebrae and with the 
sternum, allow of the motion between these parts which 
occurs in breathing. 

The combination of bone and cartilage in the ribs, their 
curved shape and jointed attachments, make them excellent 
structures for the movable walls of a box like the thorax, 
which must be, at the same time, strong, light, and springj^ 

The steyiium (Greek sternon) is a flat bone forming the 
frontal piece of the thorax. It is attached to the seven upper 
ribs. 

The pectoral and pelvic girdles. Attached to the spine and 
thoracic skeleton are the two girdles which support the 
limbs. 



44 



PHYSIOLOGY AND HYGIENE 



The pectoral girdle (Latin pectus, " chest ") consists of two 
attached bones upon each side of the thorax, the clavicle 
(Latin clavis^ '^ a key ") and the scapula. 

The clavicle, or collar bone, articulates at its inner ex- 
tremity with the sternum. At its outer extremity it supports 



C lavicle 



Humerus 




Scapula and clavicle, with end of humerus, representing 
articulation of pectoral girdle with thorax. 



the scapula. It holds the arm out from the body and thus 
facilitates free motion. In animals, as the horse, which use 
the fore limb for support only there is no clavicle in the 
skeleton. 

The scapula, or shoulder blade, a large flat triangular bone 
with a prominent spine upon its dorsal surface, lies behind 
the ribs in the back. It is held in its place by muscles and 
ligaments, and by its attachment to the clavicle. Together 



THE SKELETON 



45 



Scapula 



these bones, two upon each side, form an imperfect arch for 
the support of the arms. 

The pelvic (Latin pelvis, " a basin ") girdle, which supports 
the lower limbs, is made up of the two innominate (Latin in, 
"without," and nomen,^^ a name") 
or hip bones, one upon each side. 
Each bone attaches to the sacrum 
and arches round to meet its fel- 
low, the two together forming a 
complete arch. The cup-shaped 
cavity thus formed is called the 
pelvic cavity. 

The skeleton of the upper limbs 
consists of a series of bones. 

The humerus, a long bone, ar- 
ticulates with the scapula by a 
ball-and-socket joint. At the 
other end of the humerus two 
bones, the radius (Latin, " a> 
spoke") and idna (Latin, ''el- ^^'' 
bow"), articulate with it, form- 
ing the elbow joint. These two 
bones, which form the skeleton 
of the forearm, run parallel from 
the elbow to the wi-ist. 

The %vrist is made up of eight 
small carpal (Greek Mrpos, 
" wrist ") bones, which articulate 

with the lower extremity of the radius and with one another, 
forming the wrist joint and the lower part of the hand. 

To these bones are attached the metacarpal (Greek meta, 
" after," and Mrpos, " wrist ") bones of the hand, and to these 
the first phalanx (Greek, "battalion") of each finger and 
thumb. Each finger has three phalanges, one articulating 




Phalanges 



Arm. 



46 



PHYSIOLOGY AND HYGIENE 



to the end of the other. The thumb has two. The fingers 
are shaped and put together in the hand in a way to allow 

their doing various and del- 
icate tasks. Their varying 
length makes them fit per- 
fectly into the hollow of the 
hand. 

These bones are all articu- 
lated by joints and attached 
by ligaments. They are so 
arranged as to allow of a 
very free motion. 

The skeleton of the lower 
limbs corresponds in its gen- 
eral plan with that of the 
upper. 

The femur, corresponding 
to the humerus, articulates 
with the pelvic girdle. To 
the femur articulate the tihia 
(Latin tihia, " a flute or pipe") 
and fihula (Latin/' a buckle ") 
at the knee. Seven tarsal 
(Greek tarsos, "instep") 
bones, which articulate with 
the tibia and fibula and with 
one another, make the ankle 
and beginning of the /oof. 

To the tarsals are appended 
the metatarsals (Greek meta, 
''after," and farsos, "instep"), and to these the phalanges, 
two for the big toe and three for each of the others. 

In addition to these bones the skeleton of the lower limbs 
includes the jyateJla (Latin patina, "a pan"), or kneecap, a 



Fibula 




Tarsals 

Mttatarsali 

Phalanges 



THE SKELETON 



47 



small bone which lies in the tendon of the muscles which 
extend the leg. 

The formation of the limhs is adapted to their function. 
Since the chief function of the limbs is extended motion, 
they are made up of long bones articulated by joints which 
allow very free motion. Lightness and strength are com- 
bined as far as possible in the bones. As the arm and hand 
are used for reach and prehension, the joints are very free. 
The leg, being used for support as well as motion, is more 
firmly bound to the trunk, and the joints are less loose. The 
small bones of the foot and ankle are arranged in the form 
of a springy arch to carry the body more easily in locomotion. 
The marked differences between the two sets of limbs are 
seen only in man and the monke}' s, as it is only in these ani- 
mals that the two sets are used for such different purposes. 

The skull, or skeleton of the head and face, rests by its pos- 
terior bone, the occipital bone, upon the upper bone of the 
spine, the atlas. It is 
composed of twenty-eight 
bones. Eight of these 
form the cranium, six the 
ears, and fourteen the 
face. The cranium is a 
box for the protection of 
the brain. It is composed 
of a basal occipital (Latin 
o5, "against," and caput, 
"head") lyone, which rests 
upon the spine; two pa- 
rietal (Latin paries, " a 
waU") bones, one on each 
side, forming the crown ; 
two temjyoral (Latin tempora, "temples") bones, one on each 
side 5 a. frontal (Latin />'0)is, "forehead") bone, forming the 




Skull, 



a, frontal bone; b, parietal; c, temporal; cl, 
lower jawbone ; e, eye socket ; /, canal of ear. 



48 



PHYSIOLOGY AND HYGIENE 



forehead ; a sphenoid (Greek sj^hen, " wedge ") bone at the 
base, with an ethmoid (Greek ethmous, '' sieve ") bone in front 
of it. 

Foramina (Latin foro, " bore a hole ")• In the occipital 
bone is a large opening, the foramen magnum, through which 
the spinal cord enters the spinal canal. In the temporal 
bones are the openings to the ear cavities. Openings for the 
passage of the cerebral nerves occur in several of the bones. 
These apertures are csMed foramina. 

As the object of the cranium is protection, the bones are 
firmly united to one another by immovable joints, called sn- 

tures (Latin snere, "to 
sew"). In these sutures 
the edges of the bones are 
for the most part dove- 
tailed, the projections of 
one bone edge fitting the 
hollows of another. The 
sutures can be easily felt 
upon a baby's head. The 
bones are hard and thin, 
and are placed together 
to form an arch. The 
character of these bones 
and this method of their 
arrangement make the 
cranium an excellent shield to prevent the shock of blows 
from reaching the brain. The skull is so shaped that the 
strongest point is in front, just where the danger of a blow 
is greatest. The skull is so firm and hard that bullets some- 
times glance from it as from armor. 

The Face. The bones of the face articulate with the 
cranial bones and with one another. They consist of the 
malar (Latin mala, "cheek") or cheek bones; the maxillce, or 




I 



Bone of cranium, showing 
serrated edges. 



THE SKELETON 



upper jawbones, which carry the upper teeth; the palate 
(Latiu, "palate") bones, which together with the maxillary 
form the roof of the mouth ; the nasal (Latin 7iasiis, " nose ") 
bones, roofing the nose; the lachrymal (Latin lachryma, ''a 




Ethmoid > 



Inferior 
maxillary /j--' 



Vertical section of skull. 



tear ") bones, lying between the nasal and orbital cavities ; the 
turbinate (Latin turbo, '^a top") bones, the vomer (Latin, "a 
plowshare"), and the inferior maxillary or jawbone. 

The upright character of the human skeleton. The human 
skeleton is fashioned for an upright bearing. The head is 
nearly balanced upon the vertebral column, so that it takes 
very little muscular effort to hold it erect. The pelvis is 
broad, so that the balance of the trunk upon the lower limbs 
is easily maintained. The spine is curved and elastic, thus 
preventing the forcible transmission of the impact of the 
feet or hips with the earth to the head and brain. The 
attachments of the lower limbs to the trunk are very fii-m, 
thus allowing a secure support of the body in standing and 
locomotion. The instep arch of the foot is firm and springy, 



50 PHYSIOLOaY AND HYGIENE 

preventing the occurrence of shock when the feet strike the 
ground. 

Man a vertebrate animal. The presence of the spinal 
column, dividing the body (trunk and head) into two cavities, 
— a front or ventral one, which contains the lungs and stom- 
ach and heart, and a posterior or dorsal one, containing the 
organs of the nervous system,— places man in the class of 
animals known as vertebrates. To this same group belong 
the fishes, reptiles, birds, and beasts. Clams, insects, worms, 
and other lower forms possess no backbone and are called 
invertebrates. Man belongs to the special class of verte- 
brates known as mammals, animals which suckle their young, 
which have more or less of the body surface covered by hair, 
and which have the ventral cavity of the body entirely 
separated by the diaphragm into the thoracic cavity and the 
abdominal. Beasts, as the monkey, the dog, etc., possess the 
same organs and parts in their bodies as man. The brain 
of man is, however, much more highly developed than that of 
any beast. He possesses a mind which makes him sensible 
of right and wrong and enables him to reason. It is these 
qualities of mind which make him supreme among living 
things. 

DEMONSTRATION 

The pupil slioiild ^^sit some museum and look at the skeleton of a 
man, also at those of monkeys and of fourfooted beasts. Note the vari- 
ous resemblances in the parts and general structure of the skeletons. 



THE SKELETON 



51 



THE JOINTS 



The bones of the skeleton are placed together by means of 
joints. The joints may be immovable, as the joints of the 
cranial bones, or movable, as those of the arms and spine. 

The movable joints are contrivances which allow and regu- 
late the motion of the bones upon one another, and thus the 
movements of the body. 

The motion is secured through the agency of the muscles, 
which work the bones one upon another in these joints, just 
as the rope (sheet) attached to the boom of a boat pulls the 
boom about upon its joint with the mast. 

Structure of a movable joint. The ends of bones which 
meet in a joint are covered with cartilage, which provides a 
smooth, elastic surface 
for motion and pressure. 
These cartilages are made 
thickest upon the middle 
of the convex surfaces 
and upon the edges of the 
concave surfaces, that is, 
just in .the places where 
the wear is greatest. The 
bones are held together 
by ligaments, which lie 
above the joint. With 
the muscles they keep the 
bones in place and limit 
the motion of the joint. 

One ligament forms about the ends of the two bones, inclos- 
ing these ends and the joint in a closed sac. This sac forms 
the capsule (Latin capra, "a box") of the joint. 

On the inside of the capsule is a thin membrane, the 

HEWES, P. & H.— 4 




Joint. 



1, right hip, exterior, showing capsule liga- 
ments ; 2, left hip, showing interior of joint. 



52 PHYSIOLOGY AND HYGIENE 

synovial (Greek sun, ^^ together," and oon, ^'egg"— a fluid 
like white of egg) membrane. This secretes a fluid which 
pours over its surface and keeps the joint lubricated. (See 
Experiment 9, chapter on motion.) 

Forms of joints. The joints differ in their formation in 
accordance with the kind and amount of motion which is to 
be secured. Thus, we find baU and socket joints, allowing of 
a to-and-fro, in-and-out, and rotary motion, as the shoulder 
joint; hinge joints, as the elbow, allowing a backward and 
forward motion like that of a door ; gliding joints, as those 
between the vertebrae ; pivot joints, as that of the atlas and 
axis, allowing rotation. 

Ball and socket joint. In the shoulder joint the rounded 
upper extremity of the humerus fits into a shallow, cuplike 
fossa (Latin, ^'a ditch") of the scapula. The joint is sur- 
rounded by a loose capsular ligament and external liga- 
ments which hold the himierus to the scapula. 

Most of the movements of the whole arm take place in this 
joint, which is very free. Thus, the arm can be.carried for- 
ward and inward, that is, flexed (Latin Jfexere, "to bend") ; 
or carried backward and outward, that is, extended (Latin ex, 
" out," and tendere, " to stretch ") ; or carried toward the mid- 
line of the body, that is, adducted (Latin ad, "toward," 
and dncere, " to draw ") ; or away from the midline, that is, 
abducted (Latin ah, "away from," and dncere, "to draw"); 
or twisted round in its joint, that is, rotated (Latin rota, 
" a wheel ") ; and so forth. 

The joint is made very shallow to allow the very free 
motions of the arm. This shallowness accounts for the 
frequent dislocations of the shoulder. 

The hip joint is another ball and socket joint. Here, how- 
ever, a firm support is needed, and so the joint cup is deeper 
and the ligaments are more firm. This joint is so tight that 
the air pressure aids in keeping it in place. 



THE SKELETON 



53 



The elhow joint is a hinge joint, allowing simply flexion 
and extension. In this joint the radins and nlna move npon 
the rounded end of the hnmerus. The ulna fits to the 
humerus much as a boom fits to a mast. By this arrange- 
ment no side or rotary motion is possible. Flexion is limited 
only by the pressure of the muscles coming together. Ex- 
tension is checked by a ligament in front of the joint. 

The knee joint is on the same plan, but has larger carti- 
lages and firmer ligaments, as it is used for support as well 
as motion. 

The motions of the forearm are regulated by the action of 
the parallel bones, the radius and the ulna, upon each other. 
The radius is attached to the ulna by two pivot joints, one 
above and one below. It can be rotated upon the ulna, and as 
it carries the hand, this turns forward and backward with the 
radius, performing the motions of pronation (Latin pronus^ 
''on the front") and supination (Latin supinus, "on the 
back"), that is, the motions of turning the hand upon its 
front or upon its back. 

Forms of bones. The bones are hard, firm structures. Their 
function is support of the body, and protection 
of the soft parts which lie within their frame- 
work. Many of them form levers for the mus- 
cles to act upon in producing motion. The shape 
and character of the bones differ with their posi- 
tion and use in the body. The bones of the arm 
and leg, as the humerus and femur, are long, 
slim, and hollow, with clubbed extremities. They 
are called long bones. 

The bones of the wrist and ankle are small 
rectangular or polygonal bones. They are called 
short bones. The sternum is a flat bone. 
The ribs are flat or tabular bones. A rib 
consists of a thin plate composed of hard Long bone. 



Shoulder 
joint 
surface 



Extremity 

for elbow 

joint 



54 PHYSIOLOaY AND HYGIENE 

surface layers and a very small layer of spongy bone sub- 
stance between (Experiment 4). 

Other bones, as the vertebrae, combine the characters of 
two or more of the above forms, and are called irregular 
hones. 

The chemical composition of bone. The bones must be hard 
and at the same time tough. The}^ nnist be firm enough not 
to bend, and yet flexible enougli not to break with weight. 

To attain this combination of hardness and toughness the 
bones are made up of a compound of two substances. One, 
the mineral or inorganic substance, consisting principally 
of phosphates and carbonates of lime, gives the hardness. 
The other, the organic substance, gives the toughness and 
elasticit3^ 

If a bone be burned in a hot fire all the organic matter 
will be separated and the mineral matter left. It will have 
lost its toughness, and will break at a blow or crumble 
beneath the fingers. 

If a bone be soaked in dilute hydrochloric acid all the 
mineral matter will be separated and the organic matter 
remain. The bone will then be flexible, bending double 
witliout breaking, and so useless for support. (See Exper- 
iments 5 and 6.) 

In infancy and childhood the bones are not so hard as in 
adult life. They contain more of the organic matter, which 
makes them bend more easily. This accounts for the fact 
that children's bones are less likely to break with falls. 

Gross structure of bone (Experiments 1-3). If we examine 
a fresh long bone, as the humerus or femur, we see that it is 
a long cylindrical shaft with two large articular extremities. 
If we lift it we find that it is much lighter than it looks. 
Upon the surface of the shaft is a tough membrane com- 
posed of connective tissue and blood vessels— the periosteum 
(Greek |;e>'/, '' around/' and osteon, " bone "). This periosteum 



THE SKELETON 



55 



is the nourishing membrane of the bone. Upon its inner 
surface the deposit of new bone occurs in the growth of the 
bone. If it be stripped away the bone dies. 

The articular surfaces of the extremities of the bone are 
lined with cartilage. 

Internal structure. If we divide the shaft longitudinally 
we find that it consists of a thick, hard, compact outer layer, 
and a thin inner layer of spongy tissue, looking like a trellis- 
work of fine bony process surrounding a hollow central 
cavity. This central or medullary (Latin medulla, "mar- 
row ") cavity runs throughout the shaft. It is 
filled with soft yellow marrow. In it run blood 
vessels, lymphatics, and nerves to supply the 
bone. 

The tissue of the articular extremities is com- 
posed of a mass of spongy substance filled with 
red marrow and coated by a thin layer of hard, 
compact bone. 

This combination of hard, compact exterior 
with a reticulated interior formation and a hol- 
low center gives the bones great strength with 
small weight. If the bones were solid through- 
out they would be much heavier and less strong, 
as a tube will bear more weight than a rod con- 
taining the same amount of material.^ 

The flat bones of the body have the same gen- 
eral structure, but possess no hollow centers. 
trelliswork formation keeps the bone from jarring with the 
shock in falls. In animals like the alligator, whose recum- 
bent posture protects them from falls, the bones contain 
much less of this spongy structure. The traheculce (Latin, 




Section of a 
long bone. 

This spongy 



1 This principle is utilized in the construction of tiibular bridges. In birds the 
hollow of some bones, instead of man-ow, contains air, being connected with the lungs. 
This secures greater lightness than that of human bones. 



56 



PHYSIOLOGY AND HYGIENE 



"smaU beams") of the trellis tissue are arranged in arches 
to support the weight which the bone has to bear. 

Histological structure of bone (Greek histos, " tissue/' and 
logos, ^'discourse"— study of tissue). Histologically the 
bone is made up of a collection of cells and their processes, 
and intercellular substance in which lime salts have been 
incorporated. 

Examined under the microscope even the densest part of 
the bone proves to be simply a fine network of small bony 

plates and fibers. 
Throughout this 
network run ca- 
nals, the Haver- 
sian canals, car- 
rying the blood 
vessels for the 
nourishment of 
the tissue. These 
canals open at the 
periphery (Greek 
peri, '^ about,'' and 
pliero, "carry" — 
outer surface) and 
in the medulla. 
Around the canals in concentric lines, consisting of a series 
of plates, are the lamelJce (Latin lamina, "a plate"), which 
form the walls of the fine network. Each canal and its 
lamellae form a Haversian sy stern, and the network is made 
up of these systems. 

Between the lamellae, in a circle round the canals, are small 
cavities known as lacunce, from which radiate fine tubes, the 
canaliculi, opening into the Haversian canals, or into the 
canaliculi of other lacunae. In each lacuna lies a living cell. 
These cells are the bone cells. The plates which make the 











7>' 



Haversian sj^stem of bone. 

Dark central canals surrounded by lamellae and the dark 
lacunae with caniculi extending across the direction of the 
lamellae. 



THE SKELETON 



57 




Bone cells. 



frame of the network are made of intercellular substance 
with deposits of lime salts. The bones are constantly grow- 
ing, like any other tissue. 

Structure of cartilage. Cartilage 

lines the articular surfaces of 
many bones, forming a smooth, 
elastic surface material for the 
joints (Experiment 1). It is also 
used in connection with bone or 
alone to make up certain parts of 
the skeleton. Thus, a part of the 
shaft of each rib is cartilage. It 
is a flexible, tough substance, 
somewhat like hard rubber, and 
thus gives flexibility to the parts 
in which it is used. 

In its intimate structure carti- 
lage consists of a homogeneous 

(Greek homos, "like," and genos, "kind") intercellular sub- 
stance with cells scattered about in it. Most of the bones 

begin as cartilage, in which 
bony tissue is afterwards de- 
posited. This complete change 
of cartilage into bone, the ossi- 
fication, does not occur in some 
bones until twenty years of 
age, and even latei*. 

Ligaments are tough, some- 
what elastic bands composed 
of connective tissue. They are 
used to bind the parts of the 
skeleton, the bones and cartilages, together. They support 
organs. They form the supports and the sheath of joints. 
(See Experiment 9, p. 85.) 




Cartilage. 



58 PHYSIOLOGY AND HYGIENE 

Connective tissue is a very widespread tissue in the body, 
entering- into the formation of many parts and organs. 
Ligaments, the periosteum of bones, the fasciae and tendons 
of muscles, are composed of it, and it enters into the walls 
•of serous and mucous membranes and blood vessels and into 
the skin. Its texture may be very firm or very loose, ac- 
cording to its position or use. 

HYGIENE OF THE SKELETON 

The first requisite of a strong, agile body is a good bony 
frame. Strong muscles lose much of their efficieucy if they 
do not have strong, straight bones to act upon. Any weak- 
ness or deformity of the bony walls of the body tends to 
restrict the growth and functional efficiency of the organs 
which are protected and supported by these walls, as are the 
brain and lungs. 

Effect of good and bad habits upon the skeleton. The ossifi- 
cation of the cartilage and the bony union of the shafts and 
extremities of the bones go on during infancy and childhood. 
Complete union is not accomplislied until about the twen- 
tieth year. In thus hardening, the frame and the bones will 
tend to take the shape in which they have been allowed to 
grow. We should have care, therefore, that they are not 
influenced disadvantageously by improper habits. 

Thus, a child should not be allowed to walk until his leg 
bones are capable of bearing his weight. Otherwise the 
flexible bones may beud outward and become fixed in this 
shape, and the child thus be bow-legged. 

Children should carry the frame erect and the shoulders 
well back. The development of the thorax should be en- 
couraged by running and rowing, and exercises with the 
arms. Thus a full respiratory capacity will be developed.^ 

5 The correct position is : head up, chin in, chest expanded, shoulders back and 
dovm, abdomen in, hips thrown back. By holding this attitude in mind and prac- 



THE SKELETON 59 

Dress. All clothing which constricts the chest or waist, 
as tight waists or corsets or belts, should be discarded.^ 

Short skirts are better than long ones, as they allow a fuller 
development of the legs by permitting a freer stride. 

Tight shoes permanently deform the foot, and, by thus in- 
fluencing the gait, hinder the development of the legs. 

Seats in schools. Much harm has come in past times from 
improper methods of seating children at school. The seat 
should be of such a height that the feet touch the floor, 
else the thigh bones may become bent by the weight of the 
legs below. 

The desk should be so arranged that the child may sit 
erect while writing, to avoid the risk of a lateral curvature 
of the spinal column, or a stoop of the shoulders. 

Food. The proper development of the bones is dependent 
upon proper feeding. In improperly fed children the bones 
do not harden as they should. There is a disease common 
among children of the poor, called ricTiets, in which great 
deformities of the bones occur as a result of the lack of 
proper food. 

Fracture {hatm frangere, "to break"). When a bone is 
broken the injury is called a fracture. When this occurs a 
very interesting process ensues. From the broken ends of 
the bone a fluid substance oozes and collects about the frac- 
ture. In time this hardens to a gristle-like substance. Then 
bone begins to be formed in this substance, just as it does 
in cartilage in the original formation of bone, until in six 

ticing it faithfully for af ew days one can train the muscular sense to become accustomed 
to it, and after a time to feel uncomfortable in a stooping or crooked position. In 
sleep also the straight position should be cultivated, that the chest may have room for 
free expansion. Pillows should be only high enough to support the head at such a 
level as will hold the neck straight. 

1 It is said that the Queen of Portugal has amused herself and her friends by having 
pictures of the skeletons of the ladies of her court made by means of the X ray. These 
pictures showed the bones of the thorax so deformed, evidently by the use of the 
corset, that it made a decided impression on them, and they have determined to use 
this article of dress no longer.— Journal of Hygiene. 



60 PHYSIOLOGY AND HYGIENE 

weeks the broken parts are united by new bone just as 
good as the old. 

Dislocation. The joints are delicate structures. Their 
location subjects them to sudden and severe strains. In a 
fall, for instance, the whole weight of the body may come 
upon the wrist or shoulder. A misstep brings an unex- 
pected strain upon the ankle. Owing to the loose structure 
of the joints, these strains are likely to lead to dislocations 
(Latin dis, "from," and locus, "place"). Thus, a baseball 
striking the end of the finger pushes the inner end of the 
phalanx through or past the ligaments, " out of joint." The 
bone has then to be put back over the same course by which 
it went out. 

When the ligaments of the joint are stretched and bruised 
or torn, the injury is called a sprain. Such an injury often 
occurs from a Avi-enching of the ankle in running. 

Exposure to cold and wet. The joints are a favorite seat 
of several diseases. Exposure to cold and wet is very likely 
to cause inflammation, and is often followed by a disease 
known as rheumatism, which fi-equently affects the joints. 

Alcohol drinking. Indulgence in alcoholic liquors appears 
to have a distinctly deleterious effect upon the nutrition of 
the bones. It is a well-authenticated fact, substantiated by 
the testimony of man}^ surgeons, that in alcoholic subjects 
(heavy drinkers) the repair of fractures and other injuries 
to bones is much less vigorous than in the average patient. 
The periosteum appears unable in such cases to supply the 
proper nourishment so rapidly as in normal condition.^ 

1 As a surgeou having vast opportunities of experience in hospital and private 
practice. I must declare that I always look upon patients who have been in the habit 
of using spirituous beverages as least likely to recover from serious maladies or from 
shock follomng operations, and also as those most likely to require longer time for 
the cure of diseases of a more simple character. I have at times met with cases of 
fracture of the bones, occurring in persons of intemperate habits, in wliom the bones 
would not unite by bony material, but remained flexible or useless.— J. N. Carnochan, 
Professor of Surgery, New York Medical College, author of Contributions to Opera- 
tive Surgery. 



THE SKELETON 61 

Indulgence in alcoholic liquors is a very prominent factor 
in the causation of gout, with which is often associated a 
very serious diseased condition of the joints.^ This disease 
is common among people who are accustomed to high living, 
and especially to drinking strong wines and ales. The ten- 
dency to gout is often inherited. 

Faulty nutrition of the bones, from the use in youth either 
of alcoholic drinks or of tobacco, prevents their full develop- 
ment, and consequently affects the stature.^ 

DEMONSTRATIONS AND EXPERIMENTS 

STRUCTURE OF BONE 

1. Procure the thigli bone of a sheep, with the meat upon it. Re- 
move the meat by soaking and scraping. 

Note the pinkish-white color of the bone, which is due to the vascular 
parts of the tissue, from which all blood and lymph have not yet disap- 
pjBared. Contrast this color of bone lately living with the white color of 
old dried bone. 

Note the large, roughened ends of the bone ; the smooth surfaces for 
articulation ; the cartilage which lines these articulation surfaces. 

Note the rough places for the attachment of muscles. Somewhere in 
the length of the bone you will find a hole, which is the entrance of a 
blood vessel into the bone. 

2. Saw this bone across in the middle. Note the difference in the 
character of the compact outer layer and the " spongy " inner layer. 

1 There is no truth in medicine better established than that the use of fermented 
or alcoholic liquors is the most powerful of all the predisposing causes of gout ; nay, so 
potent that it may be a question whether the malady would ever have been known to 
mankind had such beverages not been indulged in. Stout and porter rank next to 
wine in predisposing to gout ; eider and smaller beverages will also act to some extent 
as producing causes of gout. — Dr. Alfred Baring Garrod. 

2 Children of alcoholic parents, trained to the early use of liquor, are stunted in 
their growth, and a French physician is inclined to ascribe to this fact the decref.se 
in the standard of normal height shown by statistics in that country. — Journal of 
the American Medical Association, November 14, 1896. 

Smoking prevents the healthy nutrition of the several structures of the body; 
hence comes, especially in young persons, an an-est of the growth of the body ; low 
stature, a pallid and sallow hue of the surface, an unhealthy supply of the blood, 



62 PHYSIOLOGY AND HYGIENE 

Note the central cavity with its contained soft marrow substance. 

3. Make a longitudinal section of the lower half of the bone. 

Note the archlike arrangement of the trabeculae of the spongy tissue 
in the extremity of the bone. 

4. Obtain a rib. 
Make a cross section. 

Note the difference in the structural plan of this fiat or tabular bone 
and that of the long bone examined. 

5. Composition of bone. Organic substance. 

Weigh a rib bone. Heat it in a hot coal fire for half an hour. 

Note and explain the changes which occur in burning. 

After cooling, weigh again. The loss in weight is due to the loss of 
organic matter which has burned up. The shape of the bone remains 
the same, but there is less substance. 

The bone is now easily breakable because the tough organic matter 
which gave it tenacity is gone. 

6. Removal of mineral matter from bone. 
Weigh a rib bone as before. 

Add a teaspoonful of hydrochloric acid to a pint of water. Place the 
bone in this for a few days. 

Note that the size and form do not change. 

Note the loss of weight, after drying the bone thoroughly. 

When it is taken out, note that the bone bends much more easily than 
before ; that it can now be cut with a knife. This is because the hard 
mineral matter has been removed by the acid, leaving the tough organic 
matter only. 

7. Test for the carbonates and phosphates in bone. 

Pulverize some of the bone which has been roasted and add hydro- 



and weak bodily powers.— James Copeland, M.D., F.R.S., Editor of London Medical 
Repository. 

I believe that no one who smokes tobacco before the bodily powers are developed 
ever makes a strong, \igorons man.— Fergus Ferguson, M.D. 

A record of the users of tobacco has been kept at Yale for the past eight years, for 
the main purpose of determining the number of men who began the habit while in 
college, and, from the uniformity of the records, considerable confidence has been 
felt in the resiilts obtained. The growth of the men is as follows: In weight the non 
users increased 10 4 per cent more than the regular \isers, and 6.6 per cent more than 
tlie occasional users. In the growth of height the nonusers increased 24 per cent 
more than the regular users, and 14 per cent more than the occasional users. — Pro- 
fessor J. W. Seaver, M.D., of Yale, in the University Magazine. 

Stunted growth has again and again impressed a lesson of abstinence from tobacco, 
which has hitherto been far too little regarded. — London Lancet. 



THE SKELETON 63 

chloric acid. Bubbles of carbonic acid gas will be given off. This test 
shows the presence of the carbonates. 

Add water. Filter. Then to the clear filtered solution add amnionic 
hydrate. A precipitate will fall. This precipitate consists of phos- 
phates, 

8. Proportion of water and solid in fresh bone. 

Break a fresh bone into small pieces. Weigh, dry in a current of 
Avarm air until there is no variation in the weight, and weigh again. 
Determine loss. The loss is water. 

QUESTIONS 

I. What is the function of the skeleton ? What structures and mechan- 
isms are used in its make-up, and how are they put together? Describe 
the general arrangement of the skeleton. How is the vertebral column 
built up? What is inclosed within the column? Give some idea of the 
adaptability of the spinal column to its uses. 

II. What are intervertebral disks? Where is the atlas? What does it 
support? What keeps all the bones joined together ? What is the lower 
end of the spine called? What is the thorax? What is contained within 
it? How many ribs are there? How are the ribs attached at each 
end? 

' III. What motions of the thorax do the joints and attachments be- 
tween the spine and ribs allow? Why is part of each rib cartilage? 
Where does the sternum lie? What is the pectoral girdle? How is it 
attached to the trunk skeleton? 

IV. Describe the scapula. What is the pelvic girdle? How do the 
humerus, radius, and ulna lie in relation to each other? How many 
bones are there in the wrist? Name the bones of the leg. What are 
the metatarsals? In what parts are the phalanges? 

V. Grive some idea of the way in which the structure of the limbs is 
adapted to their use. Describe the skull. What is the chief object of 
the cranium? What are foramina? How are the cranial bones jointed 
together? 

VI. To what class of animals does man belong? What is a joint? De- 
scribe a movable joint in the body. Mention a ball-and-socket joint; a 
hinge joint. What are the functions of the bones? Name several 
varieties of bones. 

VII. How is it accomplished that bones are both hard and tough and 
elastic at the same time? What happens when the inorganic substance 
is removed from a bone by acids? How do the bones of children differ 



64 PHYSIOLOGY AND HYGIENE 

from those of adults? Give a general idea of the gross and finer struc- 
ture of a bone, as the humerus. What is gained by having the, long 
bones hollow ? 

VIII. Where in the body do we find cartilage ? How does it compare 
with bone in hardness and elasticity? Of what kind of cell substance 
does cartilage principally consist ? Does cartilage ever change in the 
body? What is ossification? What are ligaments used for in the body? 

IX. When does the body take its shape? How does the knowledge in 
regard to the anatomy and physiology of the skeleton influence us in our 
habits of life? What is a fracture? What is a dislocation? A sprain? 

X. If a man and a boy each sat daily for three or four hours in a straight- 
backed chair, which would receive the more injury? Is the same true 
of tobacco smoking? Why is a fall less likely to injure a child than a 
grown person? 



CHAPTER IV 

MOTION 
I. THE ^lECHANISM OF MOTION. II. THE ORGANS OF MOTION 

ONE of the very important functions of the body is that of 
motion. In providing for its wants the body must per- 
form a variety of movements. It is moved from place to place 
by the motion of the legs. The arms are moved in supplying 
the food to the body. The lips, jaws, and tongue are moved in 
eating the food. The heart is constantly moving in pump- 
ing the blood. The food is kept moving in the stomach and 
intestines by motions of the walls of these organs.^ 

All these motions are brought about through the agency 
of a set of organs known as muscles. 

These muscles form the firm flesh which we can feel 
beneath the skin and fat, covering and filling out the whole 
skeleton. They act for support and protection of the parts, 
but their prime function is motion. Wlierever there is 
motion to be performed there are muscles provided for its 
performance. 

Each muscle is a firm, fleshy body, which has the power of 
contracting, that is, of growing shorter. You can feel in 

1 Motion is one of the forms which the energy store of the body assumes when it is 
liberated. The burning of the tissue supplies, and consequent liberation of energy for 
this purpose, takes place in the organs adapted for the accomplishment of this 
function. 

65 



66 PHYSIOLOGY AND HYGIENE 

3^our arm the firm, fleshy muscle kno^\Ti as the biceps, and 
can feel it grow larger in girth and shorter when you con- 
tract it to bend your arm. 

The muscle is often attached to bones, and by moving pulls 
one up toward another. Let us illustrate by this same biceps 
muscle. This muscle is attached to the scapula, or shoulder 
blade. From thence it runs down the arm and across the 
elbow joint to the radius bone of the forearm, to which it 
attaches Avitli its lower end. Now, when tliis muscle con- 
tracts it tends to pull the bones to which it attaches 
toward each other. But the scapula is fixed and immovable. 
So the only bone which moves is the radius, which is bent 
up on the elbow joint toward the scapula, and the arm and 
hand going with it, the whole forearm is bent (Experiment 1). 
On the back of the arm is another muscle, the triceps, which 
straightens the arm again. 

These muscles often attach to the bones by long, strong 
cords known as tendons (Latin tendo, ''I stretch"). You can 
feel at the wrist the tendons running from the muscles of the 
forearm to the fingers. They are closely packed here and 
bound down by a fibrous ring at the wrist. The big, rougli 
ends of the long bones are for the attachment of these 
muscles or their tendons. 

All muscles do not attach to bones. Some are in the walls 
of organs, like the heart or stomach, and by contracting make 
the cavities of these organs smaller. 

Antagonistic muscles. The muscles are often arranged in 
sets— one set to pull a bone or a part one way, and another 
set to pull it back. Thus, on the front of the arm are muscles 
to bend the fingers, on the back muscles to straighten them 
again. In the face there are muscles at each side of the 
mouth, keeping it in shape. If one side of tlie face be 
paralyzed the puUiug ceases on that side, while the other set 
of muscles has it all its own way, and distorts the mouth. 



MOTION 



67 



Each muscle is in reality a little engine. It is made up of 
organic substance, and contains, as we have explained in Chap- 





Flexors. and extensors of hand. 

A, fi-ont of arm: 3, biceps; 3', biceps tendon; 4, brachialis antiens; 5, triceps: all 
of upper arm. 7, flexor cai-pi radialis ; 8, i^almaris longns ; 9, flexor carpi ulnaris ; 

13, flexor snblimis digitonim; 14, flexor longus poUicis; 15, flexor profundus digitoriim; 
16, palmaris breads ; 17, abductor pollieis : all flexors of hand and fingers, bending them 
to the arm. 6, pronator radii teres. 

-B, back of aiTa: 12, extensor carpi radialis longior; 13, extensor car^n radialis brevior; 

14, extensor communis digitorum ; 15, extensor carpi ulnaris ; between 14 and 15, ex- 
tensor minimi digiti ; 18, 19, extensors internodii poUicis. All straighten hand and fingers. 

HEWES, P. & H.— 5 



68 PHYSIOLOGY AND HYGIENE 

ter II., under metabolism, a certain amount of energy stored 
up in this substance. When the muscle engine works, some 
of this organic substance is burned, and its energy liberated. 
Thus, by the burning of its fuel the muscle gets energy to 
produce its movements, just as the engine does from the 
burning of coal.^ 

The action of a muscle is controlled from the nerve 
centers. When we desire to make a certain movement, a 
message is sent from the brain along a nerve to the muscle 
which performs this movement. This message sets the mus- 
cle engine going, just as an electric current sent by push- 
ing a button starts a bell ringing or a machine running. 



I. THE MECHANISM OF MOTION 

The movements of the body by muscular action are per- 
formed for the most part through the mechanism of the lever 
system. 

The lever (Latin levare, " to lift ") is a contrivance to gain 
either greater power or greater range of motion. By press- 
ing your weight upon the long arm of a lever you can raise 
several times, say twice or thrice, this weight upon the other 
end, thus gaining power. By moving the short arm of a 
lever one foot you may move an object upon the other end a 
longer distance, say six feet, thus gaining range of motion. 

The mechanism consists of a bar, the lever, resting upon a 
fixed point, the fulcrum. If the fulcrum is in the center of 
the bar no advantage is gained either way. Thus, upon a tilt 
or seesaw, with equal parts of the board two people of equal 
weight will just balance each other. If one starts the tilt by 
a jump, the other will fall just the distance that the first 
rises. If one person is lighter, he is given more board, which 

1 When the muscles are in active use much more burning occurs, and more heat is 
produced in the body. Each of us can prove this by experience. 



MOTION 69 

enables him to raise the heavier person by his less weight ; 
but in doing it he has to ride over more distance than the 
other man on the short end. So, while the man on the long 
end moves a greater with a less weight, the man on the 
shorter end moves the long end a greater distance by going 
a less. 

It is for this second purpose, the gain in range of motion, 
that the lever system is utilized principally in the body. The 
muscles occupy the place of the heavier person on the shorter 
end of the board. They attach to the short end of the bone 
which is placed as a lever, and by moving this a short dis- 
tance move the other end of the bone, and all attached to it, 
a long distance. The muscles are strong enough for all prac- 
tical purposes, and do not need to gain power. What they 
do need to gain is range of motion, so that the hand can 
reach about the body, or the legs take a long stride, and, by 
their extra strength applied to the lever, thej can, by moving 
themselves one inch, move the end of a limb one foot or more. 

THREE CLASSES OF LEVERS. 

Levers are divided into three classes, according to the 
position of the fulcrum. 

In Class I. the fulcrum lies between the weight and the 
power. A lever of this class is seen in the mechanism of 
moving the head forward and back. Here the fulcrum is the 
atlas upon which the head rests, the power arm is the small 
part of the head behind the line of the spine, the distance arm 
the front of the head and face. The power is applied to the 
short arm by muscles stretching from the spine to the head. 

In Class II. the fulcrum is at one end with the weight 
between it and the power. When we raise ourselves upon 
our toes we use this form of leverage. The front of the 
foot is the fulcrum, the power is exerted upon the heel by 



70 PHYSIOLOGY AND HYGIENE 

the calf muscles, the weight of the body rests between and 
is raised. In this leverage we lose distance and gain power. 

In Class III. the fulcrum is at one end, with the power 
between it and the weight. 

An application of this form of leverage can be seen in 
the flexing of the forearm. 

The forearm articulates with the humerus at the elbow. 
The biceps muscle starts from the scapula above, crosses the 
elbow joint, and attaches by its tendon to the radius of the 
forearm just below the joint. 

When the biceps contracts or shortens it puUs upon the 
forearm, which is bent upon its hinge joint, and the free end 
of the arm comes towai-d the shoulder. The fulcrum is the 



p 


Lever of Class I. 




W 


p 






F 


1 




W 


A 


Lever of Class II. 






'• 


P 




\7 


w 


Lever of Class III. 




F 



joint, the weight or distance arm the forearm and hand; the 
power is applied by the muscle near the fulcrum. By mov- 
ing a short distance the part of the bone to which it attaches, 
by its contraction through an inch or so the biceps moves 
the hand on the end of the long weight arm a foot. 

The extension of the forearm is accomplished by the 
triceps muscle through a leverage of Class I. 



i 



MOTION 71 

The flexion of the hip is an application of leverage of the 
third class, similar to the flexion of the forearm. 

Walking. The movements of the loody are thus accom- 
plished by the mechanical arrangement of mnscle, bone, and 
joint. 

In walking, one leg and foot is carried forward by the 
muscles which bend the thigh upon the hip. At the same 
time the knee is slightly bent by the muscles which flex it, 
to take the toes from the ground. This foot is placed on the 
ground before the other foot has left it. The body is then 
raised on the toes of the posterior foot, chiefly by the action 
of the calf muscles pulling on the heel, and given a push for- 
ward by the toes as they leave the ground. This hind foot 
is then swimg forward in turn and grounded in time to catch 
the forward weight of the body.^ 

One side of the body tends to outwalk the other. This, 
if not corrected, w^ould lead us to walk in a circle, as people 
frequently do who are lost in the woods. 

In moderate walking very little muscular effort is used, 
as the legs swing forward after the first lift, like pendu- 
lums, of their own weight. The body is simpl}^ kept falling 
forward. 

In vigorous walking more muscular motion is brought 
into play. 

Running. In running, the legs are lifted and the body 
thrust forward by quick, vigorous action of the calf muscles 
and the extensors of the knee. 

The upright posture. The body is maintained in the erect 
standing posture by the tension of the ligaments of the 
frame and the cooperation of certain muscles. With the 
feet as a support, the flexor and extensor muscles of the ankle 
both contract, and thus hold the ankle from bending and the 

' In walking, the body oscillates from side to side, so that a man is never so tall 
when walking as when standing still. 



72 PHYSIOLOGY AND HYGIENE 

leg steady in the midline. The knee is kept stiff by the 
contraction of the extensors, which prevent flexion, and the 
ligaments of the joint, which prohibit overextension. 

The trunk is balanced in the midline, and is held there by 
the strong ligaments and muscles which pass from the pelvis 
to the thigh in front, and by the muscles behind. The head 
is held upright and in line by ligaments and by the contrac- 
tion of the muscles of the neck. 

If any change from the line is made by one part of the 
body, another part must be placed out of line in the opposite 
direction to adjust the balance. Thus, we may offset the 
tendency to fall in leaning forward by throwing the hips 
back or by putting a foot forward. 

The postures of the body are thus regulated and controlled 
by muscular action. A man who has lost his power to con- 
trol his muscles through nerve disease or through poisoning 
by alcohol reels in his gait and falls frequently. 

n. THE ORGANS OF MOTION— THE MUSCLES— CLASSES OF 
MUSCLES 

Voluntary and involuntary muscles. Muscles in the body 

are of two kinds, voluntary and involuntary. 

The voluntary (Latin voluntas, 'Hhe will") muscles are 
under control of the will. All the muscles which produce 
motion of the parts of the skeleton, as in walking, bending, 
grasping, talking, chewing, are voluntary. 

The involuntary muscles (Latin in, "not," and voluntas, 
" will") lie principally in the walls of organs and vessels, and 
by their contractions produce movements of these walls. 
Thus, the food is forced through the stomach and intestines 
by the action of the muscles in the ^^alls of these structures. 
They are controlled by unconscious nervous action, and per- 
form whether we will or not. 



MOTION 73 

The voluntary muscles are, as stated, attached by one end 
to a fixed body. This attachment is called the origin. At the 
other end they are attached to a movable body. This attach- 
ment is called the insertion (Latin inserere, "to implant"). 

Among the voluntary muscles which appear prominently 
upon the surface of the body are the biceps of the arm, the 
deltoid of the shoulder, the pectoralis major (Latin pectus, 
" chest," and major, " greater ") of the chest, the flexors and ex- 
tensors of the forearm, and the calf muscles of the leg. The 
Nceps (Latin Us, "twice," and caput, "head"— two-headed) 
flexes or bends the forearm. You can feel this muscle harden, 
and see it grow shorter and bulge out, as you bend your arm. 
You can feel the several muscles upon the front of the fore- 
arm stiffen and stand out when you close the fingers, and feel 
them soften, and the muscles on the back of the arm stiffen 
and stand out like cords, when you open the hand widely. 
The calf is made up of two muscles which are very strong, 
as they have to be to lift the whole body. They attach to the 
heel by a strong tendon, the tendon of AcJiilles. (See list, 
with plate, pp. 76-78.) 

Structure of voluntary muscle (Experiments 6-8). A muscle 
is a soft, tough mass of tissue, having, as a rule, a thick red 
central portion, with one or both ends tapering into white 
cords, known as tendons. Its appear- 
ance can be judged by looking at the 
beef in the market stalls. 

Some muscles have a tendon at one 
end only, some no tendons, attaching 
directly by their fascice (Latin fascis, " a 
bundle ") to the bones. 

The tissue of voluntary muscles is 
known as striate muscle tissue. Each 
muscle mass consists of a number of Striate muscle. 

■L n ujn iij^ • T /T !.• a, at rest (relaxed) ; b, con- 

bundles of fibers, called fasciculi (Latin tVacted, 




74 



PHYSIOLOGY AND HYGIENE 



diminutive of fascis, '^a smaU bimdle"), all bound together 
by a connective tissue sheath. Each fasciculus is surrounded 
and separated from the rest by a connective tissue sheath 
extending from the main sheath. 

Each fasciculus consists of a bundle of mnsGle fibers running 
longitudinally. 

Each fiber is enveloped in a sheath called a sarcolemma 
(Greek sarx, " flesh/' and lemma, ^^ husk ")• The fiber consists 
of a semifluid substance which, as it lies in the sarcolenmia, 





ll iioiiiijifiii ■ 
f''''J-;i]i]iiii^#]iffiM'i™ 



IPllllllllIHlIll 



i^ll! 



Section of voluntary muscle, 
fibers separated. 



Voluntary (striate) 
muscle fiber. 



has a striate (striped) appearance, showing alternate dark and 
light bands running across it. Each fiber represents a cell 
and has a nucleus. It can be teased (separated) into fine 
threads, or fihnllce (small fibers). 

In contraction of the muscle each fiber grows shorter and 
thicker, thus increasing the breadth and lessening the length 
of the whole muscle. 

The prolongations of the muscle, fasciculi, and fiber sheaths 
form the tendons, which are thus tough connective tissue 
structures. In the sheaths run blood vessels and nerves. 



MOTION 



75 



Structure of involuntary muscle. The tissue of most invol- 
untary muscles is called nonstriate or plain muscle tissue. 
This tissue consists, like the striate, of 
bundles of fibers bound together by con- 
nective tissue. The fibers, however, are 
not striped and have no sarcolemma. 
They consist of elongated cells attached 
to one another. The fibers interlace. 

The m usde of the heart differs in struc- 
ture from both the above forms of mus- 
cle. It consists of fibers striated like the 
voluntary muscle, but, like the plain 
muscle tissue, having no sarcolemma 
and interlacing with one another. 

In chemical composition the muscle 
contains a proteid substance, mineral 
salts, glycogen, and water. This pro- 
teid clots after death, causing a stiff- 
ness of the 




Fibers of involuntary 
muscle, 
a, nucleus. 




Heart muscle. 



muscular system, 
known as rigor mortis. 

In its action, as we have stated, 
the muscle burns up a portion of 
its substance.^ This substance lost 
by burning and wear and tear of 
action its cells renew from the 
food which comes to it from the 
blood, so that during rest after a 
hard day's work the muscles are 
all built up again and made ready 
for more labor. 

Corresponding to the several 
parts of the bony skeleton, the 
trunk, the limbs, etc., we have sep- 



1 The tissue burned is principally the carbohydrate store. 



76 



PHYSIOLOGY AND HYGIENE 



arate groups of muscles which regulate the motions of each 
of these parts or form part of their muscular frame. 

The important muscles of each division, most of which can 
be seen in the plate on page 77, are as follows : 



30 



17 



14 



16 



Muscles of the trunk. 
{Numbers refer to plate.) 
Erector spinae 
External oblique 
Internal oblique 
Rectus abdominis 
Intercostals 
Serratus magnus 
Trapezius ) 
Rhomboideus ) 
Latissimus dorsi 



15 Pectoralis major (chest muscle) 



moves the trunk backward, 
move the trunk forward. 

compresses the abdominal viscera. 

raise and depress the ribs. 

raises the thorax. 

move head backward ; move shoul- 
ders backward. 

draws arms downward and back- 
ward. 

draws arms across front of chest. 





Muscles of the head. 




1 


Occipito-frontalis 


moves the scalp and eyebrows. 


2 


Orbicularis palpebrae 


closes the eye. 




Levator palpebrae 


opens the eye. 


11 


Temporal 


raises the lower jaw. 


9 


Masseter 

Face muscles. 


raises the lower jaw. 


7 


Depressor labii inferioris 


depresses the lower lip. 


6 


Orbicularis oris 


draws lips together. 


10 


Compressor nares 


depresses end of nose and draws 
sides together. 


4 


Zygomaticus major 


draws angle of mouth upward and 
outward. 


3 


Levator labii superioris alae- 


raises the upper lip and side of the 




que nasi 


nose. 



Muscles of the neck. 
12 Platysma myoides 



13 



Sterno-cleido-mastoid 
Scalenus 



depresses lower jaw and lower lip. 
depresses head upon neck and chest, 
moves head and neck to the side. 




The muscular system. 



78 



PHYSIOLOaY AND HYGIENE 



Muscles of the upper limb. 
18 Deltoid (from shoulder to arm) carries arm outward and upward. 



19 
20 



22 



21 



Biceps 

Triceps 

Brachialis anticus 
I Supinator longus 
( Pronator radii teres 
r Flexor carpi radialis \ 
-^ Palmaris longus / 

( Flexor carpi, ulnaris / 

Extensor carpi radialis 

Extensor carpi ulnaris 



flexes forearm and raises arm. 

extends forearm. 

flexes forearm. 

rotates and flexes forearm. 

rotates forearm. 

flex hand at wrist, 
extend the hand. 



24 
23 



Muscles of the hand. 

Interosseous muscles 
Abductor pollicis 
Flexor brevis pollicis 



move fingers. 

draws thumb outward. 

flexes thumb. 



Muscles of the lower limb. 

V Psoas magnus (from trunk to 
thigh) 
26 Quadriceps extensor cruris 



25 Sartorius 



27 



29 
31 

28 



S Adductor longus 
Adductor magnus 
Gracilis 
Gluteus maximus 
Biceps flexor cruris 
Semimembranosus 
Semitendinosus 
Gluteus medius 
Gluteus minimus 
Tibialis anticus 

Extensor longus digitorum pedis 
( Gastrocnemius ) (calf mus- 
( Soleus ) cles) 



•\ (ham- , 
^ string 
^ muscles) 



flexes thigh (moves it forward) on 
body, or body on thigh. 

extends leg at knee. 

flexes lower limb and erects it ; has 
been supposed to be the muscle 
chiefly concerned in producing 
the crosslegged posture of the 
tailor— hence its name. 

adduct thigh— move it toward 
other limb. 

extends thigh at hip. 
flex leg at knee. 

abduct thigh— move it away from 

other limb, 
draws up foot. 

draws up foot and extends toes, 
raise body from ground upon the 

foot; raise heel. 



MOTION 79 

Hygiene of the muscles. The development of the muscles 
depends upon a proper supply of food, exercise, and removal 
of the waste formed by this exercise or muscular work. 

Use of food. As we have said, the wear of the muscle 
tissue involved in muscular work has to be made up by new 
food brought to the muscle. A man who works hard needs 
more food than one wdio rests, as he is using up more tissue. 

Use of exercise. To develop strong muscles, however, it is 
not enough to eat plenty of food. The food must be driven 
to the muscles. This assimilation of more food by the 
muscles, and their consequent development, is accomplished 
by exercise. If a man eats a large amount of food and does 
no work he will simply get fat or ill. If he exercises, some 
of the extra food wdll go to form muscle, and his muscles will 
become large and strong. 

A good amount of exercise is almost as necessary to a 
man's health as a proper amount of food or of sleep. It 
makes him stronger in muscle, heart, and lungs. .It increases 
the activity of the circulation, and thus helps to distribute the 
blood well over the body and to carry away the waste prod- 
ucts which collect in the body from the combustion of the 
tissues, which if allowed to remain cause loss of force. 

Every one wishes to grow up as strong and able as possi- 
ble. To do this he must know what things are good for him 
to eat and what things are bad, what exercise to take, and 
how to take it. 

He must choose good, nutritious food, like milk and meat 
and eggs and bread and vegetables and fruit, and not take 
in their stead pastry and sweets, which are not so useful, and 
which disorder his digestion. 

He must avoid especially all substances which may weaken 
and unfit him for work, such as alcohol and tobacco. 

Effect of alcohol upon muscular work. Alcohol, when taken 
into the body as in its ordinary use as a beverage, lessens the 



80 PHYSIOLOGY AND HYGIENE 

body's power for muscular work. This fact has been demon- 
strated by experiments upon large armies of men. 

In the British army in Africa, for instance, the experiment 
was tried of testing how far the soldiers could march when 
taking daily what were considered moderate amounts of rum, 
and then how far they could march when taking no liquor, 
and comparing the records. So also in the Army of the 
Potomac, in the American Civil War, the same experiment 
was tried with whisky.^ When the records are compared 
it is found that soldiers can endure longer marches when 
taking no liquor than when allowed their daily portion. 
These and other experiments of the same nature thus demon- 
strate that alcohol has the effect of diminishing the capacity 
of a man for muscular work, even when the alcohol is taken 
in what are generally considered as moderate amounts.^ 
From these results we are justified in concluding that the 

1 The sirdar, Sir Herbert Kitchener, and General Gatacre, in their advances up the 
Nile, have strictly foi'bidden the supply of alcoholic liquors to any of tlie troops under 
their command. We learn that they took this step on two grounds. First, on the 
ground that from long experience they were convinced that the physical condition of 
the troops would, under these conditions, be enormously improved, and the men 
would have much greater stajang power, while their dash, determination, and steadi 
ness would also be increased. The second gi-ound appears to have been that the 
mental and moral stamina of the troops would be preser\^ed in a far greater degree 
than could possibly be the case if alcohol were served out. The result has been that 
the health, spirits, and conduct of the troops have been the admiration of all those 
who have had any dealings with them, and this experiment on a large scale has been 
an unqualified success.— J. Sims Woodhead, M.D., Professor of Pathology in the 
University of Cambridge, England. 

See also Parkes (Proc. Royal Soc, No. 150, 1874) on the issue of the spirit ration in 
the Ashanti campaign. 

Hall. Kaffir War, 18.5.5-56. 

Baer, Centralbl. f. allgem. Gesundheitspflege (1886). 

2 These experiments do not controvert the accepted fact that energy may be 
derived from alcohol in the body. They show that, owing to some effect of the alcohol, 
the body cannot get a sum total of benefit in the form of muscular work from this 
energj' of the alcohol. There are experiments which show that men may do an 
increased amount of work for a very short time under the influence of alcohol ; but 
such increase is accomplished, experiments as the above show, only at the expense of 
energy or tissue which is needed for bearing sustained labor or exposure. Thus, in 
some experiments upon British regiments, the regiment which had liquor took the lead 
at the start, but was far behind at the finish. 



MOTION 81 

drinking of alcoholic liquors, even in so-called moderation, 
is a bad practice for any one who wishes to do hard work or 
endure sustained exertion. 

This knowledge is a direct contradiction to the common 
idea that a glass of liquor increases the power to work. If 
the poor man were aware of this harmful effect of liquor, it 
would keep him in many instances from spending for a 
glass of beer or ale or whisky the money which should be 
spent for strength giving foods, such as bread or meat. 

In skill and accuracy, and in the direction and expenditure 
of energy, the man who has taken no alcohol has a great 
advantage over the man who has. He is more calm in an 
emergency, and can judge better how to make his strength 
most effective. This effect of alcohol was remarkably demon- 
strated in the naval battle off Santiago, in the recent Spanish- 
American War, in the incapacity of marksmanship shown by 
the Spanish gunners, who were given alcoholic drinks under 
the false idea that it would " fortify " them for their work.^ 

Exercise. Exercise should be regular and judicious. If 
taken to the point of fatigue day after day it does harm. 

1 The attention of the civilized world has been called to the conspicuous fact of the 
accuracy of the filing of the gunners on our battle ships in the recent war with Spain. 
The contrast between the firing of the men of our navy and that of Spain was due in 
part, no doubt, to the custom that prevails on the ships of the latter, where daily 
rations of gi'og are given at all times, and when an action is going on or anticipated, 
double rations of grog are furnished to the men, while since 1862, when that custom was 
abolished by our government, no rations of liquor are allowed at any time on board 
our ships. 

The custom just alluded to as followed by Spain is true of all the na'S'ies of the 
world but ours. Yet Great Britain has abandoned the double rations of grog when a 
fight is on, and then no liquor is allowed, but in place of it supplies of water and oat- 
meal are arranged all over the ship to satisfy the thirst resulting from the heat, exer- 
tion, and smoke inseparable from a naval combat. — The Journal of the Amer. Med. 
Assoc, January, 1899, p. 174. 

It is said that a desire to excel in athletic sport has led clubs of students at some of 
the German universities to give up their ' ' morning drinking bout. ' ' They have learned 
that beer drinking stands in the way of their best physical development and the 
highest degree of athletic success. "For years sports have been in great favor. 
Some of these, such as contests between boatmen or between cyclists, require con- 
siderable energy and power of endurance. Evidently if alcohol increased strength 



82 PHYSIOLOGY AND HYGIENE 

One should not feel used up, but like taking more exercise, 
when one stops.^ During exercise more blood flows to the 
muscles than during rest. Exercise should not, therefore, be 
taken soon after meals, as the blood is needed at that time 
for the digestive organs. 

Training. People who exercise regularly establish a habit 
of the system whereby the flow of the food to the muscles, 
its assimilation there, and the oxidation of the muscular tis- 
sue, are accomplished at least cost to the organism. Such 
people are said to be in f raining. 

Even development. Every one in training the muscular 
sj^stem should guard against developing these organs at the 
expense of the vital organs, the heart, lungs, and nervous 
system. Large muscles are of little use without a strong 
heart to keep them nourished. The man who can lift a great 
dumb-bell is not so useful as the man who can lift less but 
can endure nuiscular strain longer. The real strength is in 
endurance of work and exposure, and resistance to disease. 
This is found in an evenly developed organism. 

Exercise should be chosen to develop the muscles through- 
out the body. Running develops the muscles of the legs 
rowing with a sliding seat the arms, back, and legs. Horse- 
back riding develops the legs and trunk. Swimming and 
wrestling are very excellent exercises. All vigorous exercise 
develops the muscles of respiration and the heart. 

If any group of muscles is undeveloped, special exercises 
should be practiced to develop these, as chest- weight pulling, 

tliese competitors would provide themselves witli it and iise it freely. But tliis is not 
the case. No true spoi-tsmau, either before or duriug tlie contest, touches a glass of 
spirits, experience having taught the harm he would thereby do to liimself." (Dr. 
Bienfait of Liege.) 

1 One cause of fatigue is the accumulation of the waste products of the combustion 
of the tissues involved in muscular exercise. In excessive exercise these may collect in 
the blood more rapidly than they are eliminated by the lungs, kidneys, and other ex- 
cretoiy organs. In sijch cases they act as a poison, inhibiting (preventing) the output 
of nerve or muscular energy, and tlie fatigue that we feel when this occurs Is nature's 
wai'ning to cease exercise until the waste products are eliminated. 



MOTION 83 

dnmb-bell and club swiiigins:. As a rule ont-of-door ex- 
ercises, whicli are carried on as a pleasure rather than as 
a task, should be utilized as much as possible, and supple- 
mented, if necessary, by some systematic? gymnasium work.^ 

Rest; The periods of rest should be as regular as those of 
exercise. In these periods, especially during sleep, the mus- 
cles renew the tissue which they have used up during exercise. 

Clothing. The clothing which is worn should be loose, so 
as not to restrict muscular action. It should not be too thick, 
or it will restrict the escape of the extra heat generated by 
the exercise. 

Care in bathing the skin must be observed, for an 
unclean skin hinders the excretion of the waste substances 
caused by the combustion of the muscles in action, and any 
accumulation of such waste products poisons the system and 
lessens the power of action. 

Muscular exercise is good not only for the health of the 
muscles, but for that of the whole body. A man can use his 
mind with more efficiency, has a better circulation and a 
better digestion, if he exercises regularly. The action of the 
muscles increases the circulation all over the body, and thus 
increases the elimination of waste products, whether pro- 
duced by brain activity, muscle activity, or digestive activity. 
The heaviness and inaptitude for work which are common to 
people who do not take enough muscular exercise are due to 

1 Walking is good exercise, but the aniount of benefit to be derived from walking 
depends on the way it is practiced. A slow walk over smooth pavements for a well 
person is not to be compared with a tramp through woods, over rough fields, or climb- 
ing hills. Really graceful walking is something of a fine art, and is comparatively rare. 
To walk well one should take a free and 'firm but light stride, balancing the upper part 
of tlie body alternately on each hip, but without swaying it perceptibly, and giving the 
impetus foi-ward witli a light spring from the ball of the toot. 

Bicycling has become one of the most popular forms of exercise. It is well siiited 
to people in sedentary occupations and to women. The cyclist, however, takes more 
exercise than he is aware of, or than he intends, and is particularly liable to overtax 
his sti'ength. Riding to reach a given point laid down in plans for the day, or to keep 
up with a club, or to finish a hill when very tired, but near the top, are the bicycler's 
temptations, but they should be resisted, or harm may resiilt. 
HEWES, P. <fe H.— 6 



84 PHYSIOLOGY AND HYGIENE 

the sluggishness of the circulation and the accumulation of 
waste substances, conditions which disappear with regular 
exercise. Children and adults who devote all their time to 
study or brain work, and neglect their exercise, will suffer 
for it. There is a time for all things. The most useful man 
is one who has a strong brain, strong muscles, and a strong 
heart. The object of muscular exercise is not to develop 
modern Samsons. Bodily vigor should be cultivated, not as 
an end, but as a means to an end. Intellectual and spiritual 
perfection are the real ends. The body is but the instrument. 
A flabby state of the muscles keeps the body on the verge of 
a breakdown, and therefore a poor instrument. 

Tobacco smoking or chewing diminishes the usefulness of 
the muscles, first, by hindering their development if practiced 
during youth ; second, by its poisonous action whenever prac- 
ticed. The paralyzing effect of tobacco upon the nerve cen- 
ters diminishes the amount of nervous energy which a man 
can use in moving his muscles. All smokers are familiar 
with the inertia for muscular effort which comes after smok- 
ing. Tremor of the hand is also common with smokers when 
they try to perform acts requiring steadiness. 

DEMONSTRATIONS AND EXPERIMENTS 

1. Place tlae fingers in the hollow of the elbow, and as the forearm is 
flexed, note the tendon of the biceps muscle which draws up the forearm. 

Note that the belly of the muscle swells and becomes hard in action. 

Measure the circumference of the arm over the biceps, first while the 
arm hangs free, second when the forearm is strongly flexed. Note the 
difference. 

2. Find upon the skeleton the marks of the origin of this muscle 
upon the scapula ; also the mark of the insertion of the tendon upon the 
radius. 

3. Note in the front of the wrist the prominent tendons of the 
forearm muscles which flex the hand. 

Holding the hand extended, flex the fingers, and note the motion of 
the deep muscles and tendons beneath the skin of the forearm. 



MOTION 85 

4. Note upon the back of the hand the tendons o" the extensor 
muscles of the fingers and hand. 

5. To note how the muscles and tendons act as ligaments supporting 
the bones in the joints, clinch the fist and see how the cords upon the 
back of the hand and wrist tighten, as well as those upon the front. 

6. Structure of muscle. 

Examine a piece of lean beef shank. Note the fascia which holds the 
bundles. 

Boil thoroughly. Pick the fibers apart. This will show that muscle 
is made up of many fine fibers bound together, and will give some idea 
of its structure. 

7. Get a turkey leg. Note the white cordlike tendon in the back 
of it. Pull this tendon and see how it moves the foot, just as did the 
muscle which pulled this tendon during life. 

8. If some of the very finest muscle particles of the beef (Experi- 
ment 6) are placed in a drop of water, or, better still, a drop of one 
per cent solution of common salt, the striped (striate) character of the 
fibers can be made out under the microscope (two hundred diameters). 

9. Structure of a joint. 

Get a joint of a fowl with the two bones. 

Note how the muscles and tendons cross it from the bone above to 
the bone below. 

Note the action of these muscles and the joint. 

Note the ligaments which hold the bones together at the joint. 

Cut through the capsule of the joint. 

Note the smooth surfaces of the bone, lined with cartilage and moist 
with synovial fluid, and how they glide one upon the other. 

10. Study the action of joints. 

To illustrate the combined action of muscles and joints in regard to 
mechanism and force, the school should be provided with a "joint 
apparatus." A description of such an apparatus and the experiments 
which maybe made with this apparatus will be found in the "Outlines 
of Requirements for Harvard." 

11. Proportion of water and solids in muscle. 

Cut up some fresh muscle. Weigh and dry it until the weight re- 
mains constant. Determine loss of weight. 

12. Demonstration. 

To a nerve muscle preparation from the hind leg of a dead frog at- 
tach a recording apparatus. Apply a single electrical shock to the 
muscle. Note result. Apply single shock to nerve. Note result. 

Apply rapid succession of shocks to nerve. Note result. 



86 PHYSIOLOGY AND HYGIENE 



QUESTIONS 

I. "What are the organs of motion ? Where does the energy for this 
motion come from? How is it liberated? Describe a muscle. What is 
the characteristic property of muscle? Describe the method by which 
a muscle, as the biceps, accomplishes a motion of the part (the forearm). 
What are the rough places upon the ends of the bones for? What is 
meant by antagonistic muscles? 

II. Where is the action of each muscle controlled? Upon what system 
is the physical mechanism of motion in the body based? Describe a lever. 
What are the objects of the utilization of a lever? For which purpose is 
it principally used in the body? Describe some motion of your body 
illustrating each of the three classes of lever. Describe the act of 
walking. 

III. How is muscle classified according to its mode of action? Where 
are the muscles of eacli class found? Describe the structure of voluntary 
muscle. What are tendons? What is the tendon of Achilles? What is 
the origin of a muscle? The insertion? Describe the structure of in- 
voluntary muscle. What kind of muscle is heart muscle? What is 
rigor mortis ? 

IV. What is the chief requisite in regard to the food for purposes of 
muscular development? What practice besides the eating of sufficient 
amounts of food is necessary for the full development of muscle? 
What is the effect of the taking of alcoholic liquors during long periods 
upon the capacity for muscular work ? 

V. What kind of exercise is best? What muscle in the body is it most 
important to have strong and sound? What is the best time for exer- 
cise ? How much exercise should be taKen at a time ? 

VI. When a man wishes to move a heavy stone too large to lift, what 
instrument does he employ? What is the mechanical principle involved 
in the use of this tool ? What is the principle used in attaching a horse 
to a pole running through a central axis, as in the moving of a house 
along a road? Give some illustrations of the utilization of this principle 
in the body. Can you move both the upper and the lower jaws? 



CHAPTER V 

THE NUTRITION OF THE BODY 

I. FOOD. 11. THE DIGESTIVE ORGANS. III. DIGESTION AND 
ABSORPTION. IV. CIRCULATION AND ASSIMILATION. 

THE maintenance of life means the maintenance of 
activity of some kind. Man is constantly using his 
mnscles in motion and locomotion. The brain is constantly 
active in directing these movements and in thinking. Even 
in sleep, the cells of the body are in constant activity regu- 
lating metabolism and the transformation of energy; the 
blood is being circulated by the heart action, the air is being 
breathed in and out. 

Need of food. All this constant activity means the ex- 
penditure of much energy. As described in an earlier chap- 
ter, the energy for work is supplied in the body by the 
combustion of the tissues themselves. The stored-up '' lateyit 
[Latin latere, " to lie hid "] energy" of tissue substance is con- 
verted to ^^ dynamic [Greek dunamis, ''force"] energy" for 
work and heat by the oxidation of the substances with the free 
oxygen breathed in through the lungs. The process entails a 
constant wasting, a burning up of tissue substances. This 
waste has to be provided for by a constant replacement of 
the decomposed substances with new substances of the same 
kind ; that is, the tissues must grow as fast as they waste, 
otherwise the body would wear out and life would cease. 

87 



88 PHYSIOLOGY AND HYGIENE 

The material for the constant renewal of tissue the animal 
gets in his food. By the frequent taking in of a food snpply, 
sufficient when burned in the body to produce as much energy 
as is used there and to repair the nitrogenous waste, the 
equilibrium of the organism is maintained. 

I. THE FOOD 

Constitnents of animal food. The tissues are made up of 
combinations of certain elements. As stated on page 21, 
these are principally carbon, nitrogen, oxygen, hydrogen, 
sulphur, sodium, potassium, calcium, chlorine, phosphorus, 
iron, and magnesium. 

Since these elements are the constituents of the tissues, 
they must be the constituents of the food which is to renew 
the tissues. 

Need of organic foods. The body is unable to take up in 
their pure or separate state some of these constituents which 
it needs for the building up of its tissues. Thus, it cannot 
take up the element nitrogen from the air, in which this sub- 
stance exists in its free state, and it cannot use pure carbon 
(charcoal) as a food. 

To use these substances the body has to get them in pre- 
viously prepared combinations with hydrogen and oxygen. 
Some of these combinations, known as organic foods, can be 
taken up by the body and broken up within it; and the 
nitrogen and carbon which are contained in them can then be 
used by the tissues as they are liberated by this breaking up 
of the organic substances. 

So while the body takes some elements and some food sub- 
stances in the simple form in which they exist in the air and 
soil, as free oxygen from the air, hydrogen and oxygen in 
water, sodium and chlorine in salt, the greater quantity of 
the necessary food substances is taken in the form of com- 



THE NUTRITION OF THE BODY 89 

binations, similar in character to those which exist in the 
body, that is, in the form of organic substances. 

Thus, most of our foods we take as compounds of carbon, 
hydrogen, and oxygen, known as carbohydrates and fats, or 
of carbon, hydrogen, oxygen, and nitrogen, known as proteids. 
These compounds are built up from the elements in the air and 
soil by the plants, and we get them in vegetables and fruits, or 
in flesh, milk, or eggs, from the bodies of other animals which 
have eaten the plants. They are called organic foods} In 
taking them we get not only the use of the nitrogen, carbon, 
and other elements contained in them for repair of our tissue, 
but also, as stated on page 27, the use of the energy which is 
stored up in them in their production by the labor of the 
plants. This energy of the foods is liberated for work in 
the body when the food is combined with the tissues and 
burned. This combination and this combustion, as we have 
seen, are carried on continuously by the tissue cells. 

Classes of foods. The organic foods, as stated, are of three 
classes— ^rofeic?,^, carbohydrates, and fats. 

Proteids (Greek protos, "first"— most important) are sub- 
stances consisting of carbon, hydrogen, oxygen, nitrogen, 
and sulphur. The chief proteids of food are the gluten of 
flour and many vegetables, the albumin of eggs, the casein 
of milk, the myosin of meat. Proteid elements are the es- 
sential constituent of the body tissues. As they alone of the 
organic food substances contain nitrogen, they are abso- 
lutely essential in the food supply. As they also contain the 
other important constituent elements of the body, carbon, 
hydrogen, and oxygen, man can subsist upon proteid food 
alone, with the addition of water and mineral salts (Experi- 
ment 5, p. 122). 

Carbohydrates are compounds of carbon, hydrogen, and 
oxygen. The chief carbohydrates of food are the starch of 

1 See definition of organic substances, page 20 ; also Experiment 4, page 122. 



90 PHYSIOLOGY AND HYGIENE 

flour, rice, potatoes, cereals, the sugars of fruit, cane sugar, 
glycogen, cellulose of grains (Experiments 7 and 8, p. 123). 
; Fats are compounds of carbon, hydrogen, and oxygen.^ 

The chief fats of food are butter and cream from milk, fat 
of meat, oils. 

Both carbohydrates and fats enter into the forrftation of 
the body tissues. Neither food is absolutely essential to the 
renewal of tissue, however, as either can be built from pro- 
teids. As these foods contain no nitrogen, the tissues cannot 
be sustained upon them alone. They are of great use for 
the acquirement and production of energy in the body, as 
they contain much latent energy and are easily broken up 
to liberate it. 

In addition to the organic foods man must have water and 
minerals. Water he gets in most foods (Experiment 10, 
p. 123). Thus, many vegetables contain eighty per cent of 
water in their substance. In addition man does and should 
drink a certain amount of extra water. 

The mineral salts he gets from his organic foods (Experi- 
ment 11, p. 123). Thus, the sodium chloride, phosphates and 
carbonates of calcium, magnesium, iron, and so forth, are 
contained in the milk and meat and grains and vegetables. 
One salt, the chloride of sodium, he takes separately as 
common salt. 

Quantity and proportion of foods in diet. A man must take 
as much food as he uses up. A man who works needs more 
than a man who stays in bed or one who loafs. In doing more 
work he uses more energy, and the production of this energy 
entails greater waste of his tissue, which has to be replaced. 

A man with moderate exercise uses up in a day about four 
thousand grains of carbon and about three hundred grains 

1 In carbohydrates the hydrogen and oxygen are combined in the same proportion 
as in water, i.e., two of hydrogen to one of oxygen ; in the fats the hydrogen and 
oxygen are not combined in the same proportion as in water (Experiment 9, p. 123). 



THE NUTRITION OF THE BODY 91 

of nitrogen. This is the amount which comes away as 
waste, the carbon in carbon dioxide, the nitrogen in urea, 
and this is therefore the amount which must go into his food. 
If he takes more carbon or nitrogen than he needs it will do 
him no good, but simply make more work for his organs. 
^ Choice of food. So in choosing his food he must try to get 
a combination which contains these amounts of carbon and 
nitrogen, but not much more of either. To do this he has to 
make his meals of several kinds of food, as most foods do not 
contain in the right proportions all the substances which we 
need. Thus, bread contains both carbon and nitrogen, but 
in such proportions that a man has to take twice the neces- 
sary amount of carbon to get the necessary nitrogen. A man 
would need four pounds of bread a day to subsist on bread, 
which, besides giving him the extra carbon to dispose of, 
would necessitate his eating a large bulk of food and over- 
taxing his digestion. 

Meat alone, to give the necessary amount of carbon, would 
contain three times the amount of nitrogen required. 

If, however, a man combines bread and meat, or meat and 
vegetables, he can get the proper amount of the necessary 
elements into his body without marked excess of any kind. 
That is the reason that men live on a mixed diet} 

There are some foods, as milk, which contain the carbon 
and nitrogen in proper proportion ; but in taking enough milk 
to supply the body an adult has to take an excessive quantity, 
and gets more mineral salts and fat than he needs. The 
growing infant needs these salts and fat, and thus thrives on 
milk. 

Certain vegetables, beans or peas for example, contain 
nitrogen and carbon in about the proper proportions. 

1 The Eskimo lives upon animal food alone, the Hindoo \ipon vegetable food; but 
experience teaches ns that the peoples of the world who have accomplished most are 
those who use both kinds of food. 



92 PHYSIOLOGY AND HYGIENE 



II. THE ORGANS OF DIGESTION AND ABSORPTION 

How the food gets to the tissues. We have seen that the 
material necessary for the production of the body tissues, and 
of the energy to keep the life going, is supplied to the cells 
by the ingestion (Latin in, ''in," and gerere, "to carry") of 
food. In order that this food which we eat may be of use to 
the organism, it has first to be digested (Latin dis, " apart," 
and gerere, '' to carry "), then absorbed (Latin ah, " from," and 
sorhere, " to suck up ") and carried to the cells, where it is as- 
similated (Latin ad, "to," and similis, "like"— to make like). 

The food is first taken into the alimentary canal, consisting 
of the mouth, stomach, and intestines. Through the walls of 
this canal it is absorbed into the blood, and carried by this 
to the lymph, from which the ceUs take it up.^ 

Object of digestion. The food, like all substances, is made 
up of a combination of minute particles, called molecules. 
The waUs of the alimentary canal may be likened to a very 
fine sieve. Through this sieve the molecules of the food 
must pass before they get to the blood. Now, the molecules 
of most of our food substances are too large to go through 
the sieve ; so the food substances have to be changed in the 
canal to other substances with smaUer molecules before they 
can be absorbed. This process of the transformation of the 
food into solable, diffusible materials is called digestion? 

1 It must be understood that the real latilization of the food is in the cells of the 
various tissues. The digestion and circulation, and the organs which accomplish these 
functions, are useful merely to prepare the food for the cells, and to get it to them. All 
higher animals have organs of this kind, because the cells are so placed that the food 
lias to be brought to them. In verj' low forms of animal life (as the amoeba), however, 
there is no digestive or circulatory system. The cell takes up the food directly from 
the water or earth about it, wherever it comes in contact with any food, just as the 
cells in our body take the food up from the blood or lymph. 

2 Thus, the proteid substances of meat and bread, the albumins and so-called native 
proteids, will not pass the membrane of the intestine into the blood. They have first 
to be digested to peptones, which will pass through these animal membranes. 



THE NUTRITION OF THE BODY 



93 



The process of digestion and absorption is reaUy far 
more complex than this description implies. The intestinal 
walls are not a true sieve. The absorption is due to the ac- 
tivity of the living cells, which pass the substances through 
them. But the food first does have to be broken into smaller 
molecules to get through the cells, and thus the process is 
analogous to the straining through a sieve (Experiments 
15, a, h, 16, 17, pp. 125-127). 

The alimentary tract. Digestion of the food takes place, 
as we have said, in the organ or series of organs known as 
the alimentary (Latin alere, ^'to nourish") tract or canal. 

This canal, starting with the mouth, includes the structures 
known as the pharynx, esophagus, stomach, and intestines. Con- 
nected with it are several structures known as glayids, which 
assist in its function, as the salivary glands (Greek sialon, 
"spittle"), liver, smd pancreas. The whole combined struc- 
ture of canal and glands forms one great digestive organ. 

The mucous membrane. The whole alimentary canal is 
lined, with one continuous membrane, known as the mucous 
membrane. This mem- 
brane is lined with an inner 
layer of epithelial cells of 
cubical or cylindrical shape, 
which secrete a fluid sub- 
stance known as mucus. 
Besides the epithelial layer 
or layers, the membrane 
consists of an under layer of connective tissue carrying nerves 
and vessels. The walls of the canal include this mucous 
membrane, and in most parts outside layers of plain muscu- 
lar tissue, which give them motion. The stomach has three 
muscular layers, the intestines two layers. 

Glands. Throughout the whole length of the canal are 
structures called glands; these manufacture substances 




Mucous membrane. 



94 



PHYSIOLOGY AND HYGIENE 



and pour them into the canal to aid in digestion and ab- 
sorption. These glands may lie in the mucous membrane 

of the canal, as the gas- 
tric glands, or form 
separate isolated struc- 
tures, as the liver. 

In structure, a gland 
consists of a collection 
of epithehal cells built 
up in connective tissue 
around a well or duct. 
The simplest gland is 
merely a blind tube lined 
with secreting cells. It 
looks like a well, the 
cells lying about the wall 
like the stones in the wall 
of a well. Many glands 
consist of clusters of 
these short blind tubes 
branching out from 
one another, all built 
up by connective tissue 
into a separate struc- 
ture with nerves and 
blood vessels. Such are the racemose (Latin raeemus, "sl 
bunch of grapes") glands, as the pancreas and salivary 
glands. 

Secretion. The epithelial cells of the gland take up sub- 
stances from the blood, and transform them into a new 
substance known as the gland secretion (Latin secernere, ''to 
separate"). This they pour forth from their duct into the 
digestive canal. If we examine the secreting cells of glands 
like the salivary at a period when no digestion is going on in 




Glands iu mucous membrane. 



THE NUTRITION OF THE BODY 



95 



the part of the canal supplied by these glands, we see that the 
protoplasm of the cells is filled with abundant granules. 
During digestion these granules disappear. They repre- 
sent, together with the water and salts which are secreted 
by tlie cells, the material of the secretion. 

The mouth. The process of digestion begins in the mouth. 
The mouth cavity contains the teeth, the tongue, the palate, 
and a digestive secretion, the saliva. 

The teeth are hard, bonelike structures attached to the 
jaws. Each tooth consists of a crown and Jangs. In its 




a 





Teeth. 
a, incisors ; b, canine ; c, bicuspids ; d, molars. 



center is a cavity filled with soft pulp. The substance of the 
teeth is known as dentine. The crown, which is the part 
uncovered, is capped with a very hard substance known as 
enamel. Over the fangs, which are imbedded in the gums, is 
a substance known as cement, which cements the fang to 
the periosteum of the jawbone in the fang socket. Nerves 
and blood vessels enter the tooth by a central canal to the 
pulp cavity. 



96 PHYSIOLOGY AND HYGIENE 

The two sets of teeth. Man has two sets of teeth— one the 
milk teeth, coming in infancy, a second the permanent teeth, 
replacing these in adult life. The adult has thirty-two teeth, 
sixteen in each jaw, and eight in each half of the jaw. In 
each jaw the four middle teeth are chisel-shaped for cutting 
the food ; they are called the incisors (Latin incidere, '' to cut ")• 
Next to these on each side comes a pointed tooth, the canine 
(Latin canis, ''dog"— like a dog tooth); then two Ucuspids 
(Latin his, ''twice," and cuspis, "spear"— two-pronged) on 
each side, with double crowns and forked fangs ; last, three 
molars (Latin niola, "mill"), or grinders, which have large, 
rough crowns for crushing the food, and several fangs. 

The milk teeth are twenty in number— two incisors, one 
canine, and two molars on a side of each jaw. They come 
during the second year, and drop out to make way for the 
permanent set in the sixth or seventh year. • 

The tongue is a movable muscular organ covered with a 
mucous membrane. In this membrane are situated the 
organs of the sense of taste. In health the surface of the 
tongue is red and moist. 

The digestive secretion of the mouth, the saliva, is a viscid, 
watery, alkaline fluid. It is poured into the mouth from the 
orifices of the ducts of three pairs of glands, the parotid (Greek 
para, "near," and ous, "ear"), the suhmaxiUary (Latin sub, "un- 
der," and maxilla, "jaw "), and the suUingual (Latin sub, " un- 
der," and limjua, "tongue") glands, situated in the tissues of 
the throat and neck. The parotids, just below and in front 
of the ears, are the glands which are swollen in the mumps. 

Mastication (Latin masticare, "to chew"). The work of 
the mouth in digestion is principally a mechanical one. By 
movements of the lower jaw the food is broken up between 
the teeth. This is called mastication. The food by the same 
process is thoroughly mixed with the saliva and softened. 
This food is then collected by the action of the tongue and 



THE NUTRITION OF THE BODY 97 

cheeks and thrust into the back of the mouth. By the con- 
traction of the muscular walls of the fauces, the bolas, or ball 
(Greek hoJos, ^'a mass"), of food is then squeezed into the 
pharynx, the soft palate, or uvula, a tissue curtain which 




Dissection of face, showing parotid gland with duct leading to 
the cavity of the mouth, and submaxillary gland. 

p, parotid ; sm, submaxillary ; d, duct of parotid ; n, nerves (branches of facial) ; 
/, artery of the face. 

you can see hanging from the roof of the mouth at its pos- 
terior end, being raised. 

The pharynx is a cavity connecting the mouth with the 
esophagus. The uvula (Latin uva, " grape ") shuts it off from 
the mouth. Above it is entered by the posterior openings of 



98 PHYSIOLOGY AND HYGIENE 

the nose cavities, at the sides by the Eustachian tubes con- 
necting with the middle ear, in front below by the larynx, 
behind by the esophagus. The epiglottis (Greek epi, " upon," 
and glottis, " glottis") is a fold of tissue which extends from 
the walls of the larynx aeross the opening from the pharynx 
to the larynx, and shuts off the larynx and windpipe from 
the pharynx while food is passiug. When not perfectly 
closed the food may get into the windpipe. This is what 
occurs when food '' goes the wrong way." 

Deglutition (or swallowing) (Latin (leglntire, ^Ho swal- 
low "). The food is carried through the pharynx by the con- 
tinuation of the muscular action of swallowing begun at the 
fauces, and is forced into the esophagus. It is then forced 
along the esophagus by the action of the muscular walls, and 
into the stomach. The first part of swallowing, the forcing 
of the food through the fauces, is voluntary. After the food 
reaches the opening of the esophagus the swallowing goes on 
without our conscious control. 

The esophagus (Greek oiso, '^I shaU bear," and jyJiagein, 
^'to eat") is a muscular tube which runs along the spine 
from throat to stomach. Its walls contain striate and plain 
muscular tissue, which aids in the progress of the food. 

The stomach is a dilated pouch of the alimentary canal lying 
in the upper part of the abdomen, and rests just below the 
ribs on the left side. In structure its walls consist of a 
mucous membrane and three layers of muscular tissue 
about it. 

The mucous membrane of the stomach is lined with a single 
layer of cylindrical epithelial cells. Throughout the surface 
of the membrane are numerous shallow pits, into which open 
the ducts of the gastric glands which lie imbedded in the 
membrane. (See diagram, p. 94.) 

The principal secretion of the stomach is a watery acid 
fluid known as the gastric juice. 



THE NUTRITION OF THE BODY 



The food enters the stomach bj'^ the opening from the 
esophagus, the car^Ziac (Greek kardia, '^ heart"). Here it is 
thoroughly mixed with the secretions by the motions of the 
stomach walls, and digested. It is then pushed, by the mus- 




Section showing course of food through pharynx and esophagus. 

A, cavity of mouth showing teeth; B, epiglottis; C, pharynx; D, esophagus; 
U, soft palate ; F, nasal cavity ; S, S, spine. 

cular action of the stomach walls, through the passage from 
the stomach to the intestines, the pijlorus (Greek jmle, '' gate," 
and oiiros, "keeper"). This pylorus is an opening bounded 
by a firm muscular rmg. During digestion in the stomach 

HEWES, P. & H.— 7 



100 



PHYSIOLOGY AND HYGIENE 



the opening' is closed most of the time by the contraction of 
the muscle. From time to time it relaxes and allows a little 

digested food to pass through. 
When all the food is digested as 
far as it can be in the stomach, 
the whole mass passes into the 
intestine. 

The intestine (Latin intns, 
''within") is divided into the 
small intestine and the large in- 
testine. It consists of a tube 
twenty-five feet in length, lying 
mostly in coils in the abdomen, 
below the liver and stomach. 
The coils are supported by folds 
of connective tissue known as 
the mesentery (Greek w^fsos, ''mid- 
dle," and enteron, "intestine"), 
which carry blood vessels to the 
intestines. Externally both the 
stomach and the greater part of 
the intestine are covered with the 
serous co^'ering of the abdominal 
cavity, the peritoneum [Greek peri, 
" around," and teino,^^ I stretch "). 
The walls of the intestine consist of a mucous membrane 
and two la^^ers of muscular tissue external to this. 

In the small intestine the mucous membrane lies like a 
loose sleeve in folds or tucks called valvulce conniventes. The 
membrane is filled with numerous small glands, the crypts of 
Lieherkiihn, which open among the cells of the lining epithe- 
lium. Between the glands the membrane is raised into many 




Stomach and intestine. i 

a, stomach ; h, cardiac orifice ; c, py 
lonis ; d, duodenum ; e, large inte's 
tine ; /, small intestine. 



1 This cut is diagrammatic and does not give exact positions or relations of the organs 
included. 



THE NUTRITION OF THE BODY 



101 



small processes called vilU, which give to the surface of the 
intestine the appearance of velvet. 

The villi (Latin villus, '^ a nap of cloth ") are organs for 
the absorption of the digested food. Each villus is a minute 
pillar or conical elevation made up of connective tissue lined 
with the epithelial cells 
of the intestinal mem- 
brane, and carrying 
blood vessels and a lym- 
phatic vessel known as 
a lacteal (Latin lac, 
"milk"). The food is 
passed through the cells 
of the villus wall, col- 
lected in the lacteal and 
efferent vessels, and 
borne away to the blood 
stream. The intesti- 
nal wall also contains 
collections of glands 
called Peyer's patches. 

Besides the secretions 
from the crypts of Lieberkiihn and other glands which lie in 
the wall, the intestine is also supplied by secretions from two 
large glands which lie separate from it and empty into it 
by ducts, the liver and the pancreas (G-reek pan, " all/' and 
kreas, '^ flesh"). 

The liver is a large gland which lies beneath the diaphragm 
(the 'large muscle which forms the floor of the thoracic 
cavity and the roof of the abdominal cavity) and ribs, mostly 
on the right side of the abdomen. A secretion of this gland, 
the Ule, is poured into the intestine during digestion. It aids 
in the digestion and absorption of the food, principally the 
fats. From the blood which is brought to the liver by its 




Villi in mucous membrane of small 
intestine. 

a, lacteal ; b, blood vessel (vein) ; e, epithelial 
cells ; g, glands. 



102 PHYSIOLOGY AND HYGIENE 

afferent vessels, the hepatic artery and portal vein, substances 
are taken np by the liver cells and formed into certain prod- 
ucts known as bile and glycogen. The substances are taken 
from the blood on one side of the cells, combined, and the 
compound formed is discliar ged as bile into ducts on the 
other side of the cells. These ducts finally bring the bile 
to a large duct, the hepatic duct, which runs into the in- 
testine. 

Connected with the bile duct is a large bladder, the gall 
bladder. The bile is secreted continuously. During digestion 
it is poured into the intestine. At other periods it is stored 
in the gall bladder, from which it is discharged when diges- 
tion is on again. The bile is, in part at least, an excretion in 
which waste is removed from the blood. It is useful in part 
also as a secretion facilitating the digestion and absorption 
of fats in the intestine. 

The pancreas is a gland lying in the bend of the small 
intestine. It consists of clusters of blind tubes lined with 
cubical cells, all uniting in a large duct which enters the 
intestine. 

The partly digested mass of food from the stomach, the 
chyme, enters the upper intestine through the narrow con- 
striction of the stomach, the pylorus, which relaxes to allow 
it to pass. Here it is mixed with the intestinal secretions, 
such as the bile and the pancreatic juice, and further di- 
gested. As tlie now well-digested food is forced along by 
the contraction of the muscular walls of the intestine, much 
of it is absorbed by the villi and intestinal cells. The resi- 
due is forced along into the large intestine. 

The large intestine is separated from the small by a valve, 
the ileoccecal valve. Just beyond this valve lies the pouch 
caUed the appendix. This appendix is a rudimentary struc- 
ture corresponding to a useful one in the lower animals. 

The wall of the large intestine, Hke the waU of the small 



THE NUTRITION OF THE BODY 103 

intestine, consists of mucous membrane and muscle layers. 
Tlie membrane is fiUed with tubular glands, but contains 
no villi. 

The muscles of the walls are arranged in three longitudi- 
nal bands. The contents of the small intestine, the food 
which has escaped absorption there, the indigestible residue, 
and the detritus from the intestinal walls and the blood, are 
passed along the large intestine. Here more food and most 
of the water are absorbed. The residue is passed on as a 
thick mass to the rectum, where it is expelled Sisfceces (Latin 
faex, ^'di-egs")- 

HYGIENE OF THE ORGANS OF DIGESTION 

The members of the body rebelled against the Belly, and said,'' Why 
should we perpetually engage in ministering to your wants, while you 
do nothing but take your rest and enjoy yourself in luxury and self- 
indulgence?" The members carried out their resolve, and refused their 
assistance to the Belly. The whole body quickly became debilitated, 
and the hands, feet, mouth, and eyes, when too late, repented of their 
folly.— ^sop. 

The action of the organs of digestion and absorption is 
regulated by what is known as an automatic ("self-acting") 
nervous mechanism, and is beyond our conscious control. 
We simply provide the proper food at the proper intervals, 
and the digestion goes on witliout our giving any thought to 
the process. In fact, beyond attending to the thorough mas- 
tication of the food and the swallowing of small amounts at a 
time, the less we think about the process of digestion the 
better.^ 

But although we do not control this function, we can, by 

1 The mind has a marked influence upon the process of digestion. Strong emo- 
tions, such as fear, anger, or grief, at mealtime destroy both the appetite and the 
power of digestion. Business cares and anxiety brought to the table counteract the 
best efforts of the best of cooks. All unpleasant topics or remarks should be accounted 
hygienic sins. Mealtime is the time for fun and laughter, for pleasant stories and 
amusing anecdotes. 



104 PHYSIOLOGY AND HYGIENE 

care in diet and in the practice of eating, influence to a great 
extent the health of the organs and the efficacy of their 
function. We must eat plenty of food in order to provide 
for the body needs ; but in so doing we should alwa^^s choose 
and take the food in such a manner as to avoid injuring 
the digestive organs, and to make their work as easy as 
possible. 

In the fii*st place, we must have our food as digestible as 
possible. It is foolish to use up the energy of the organs 
and perhaps injure them by giving them some indigestible 
substance like green apples or tough meat, when we can get 
as much or more nourishment from some easily digestible 
tootV 

Mastication. We can aid in the digestion of the food by 
chewing it thoroughly. Food which is broken up into fine 
particles and softened is more easily digested, as the diges- 
tive juices can ^et at it better. If we swallow large pieces 
of meat or bread they are very slowly digested, and thus bur- 
den and perhaps injure the stomach. 

Care of the teeth. To chew our food thoroughly we must 
have good teeth. If the teeth are not properly cared for 
they decay, and thus we may lose them. If the food sub- 
stances which collect about them in chewing are allowed to 
remain there, they undergo a process of fermentation or 
decomposition, and form substances which are injurious to 
the teeth. The teeth should be thoroughly brushed at least 
twice daily. Some harmless tooth powder recommended by a 
competent dentist, or a good soap, should be used as often as 
necessary to keep them free from tartar. The particles of 
food which collect between the teeth should be removed by 
some soft thread, as floss. Neglect of cleanliness, besides 



1 Some indigestible residue is useful (see p. 138). Thus, the residue of fruits and 
vegetables keeps the intestines in working order. But the above principle is to be fol 
lowed in general. 



THE NUTRITION OF THE BODY 105 

facilitating decay, permits a substance known as tartar to col- 
lect upon the teeth, which helps to loosen and destroy them. 

People with poor teeth frequently suffer from indigestion, 
as the food cannot be broken up into small pieces before 
being swallowed, or collects some of the foul decomposi- 
tion products from the mouth, which irritate the stomach.^ 

Cooking. To make our food more digestible most of it 
is prepared by cooking. This process disintegrates and 
softens the food, so that we can more easily break it up in 
the mouth and stomach. Thus, the nutritious muscle fiber 
of meat is separated from its indigestible connective tissue 
supports. The hard shells of corn and oats are softened and 
separated. 

Cooking also brings out the flavors of food substances and 
makes them more appetizing. 

Eating too fast. The food should be chewed slowly and 
swallowed in small amounts, as the stomach can take care of 
the food better if it receives it a little at a time. There is no 
more common cause of indigestion than rapid eating. 

Drinking. Large amounts of liquid should not be drunk 
with our meals, as this dilutes the digestive juice and delays 
digestion. A glassful of water may be sipped with the meals. 
An equal amount of water should be taken in the same 
manner between meals. 

Overeating. We must be moderate in the quantity of food 
which we eat. Stuffing overloads and stretches the stomach, 



1 Forty newsboys, ranging in years from fifteen to eighteen, applied recently for 
appointments in tlie United States naval service. Thirty-eight out of the forty were 
rejected on account of physical defects, the cause of rejection in most cases being 
unsoundness of the teeth. 

Savages have stronger teeth than civilized men, owing probably to the fact that they 
eat harder food, which exercises the muscles and bloodvessels of these parts and keeps 
them well supplied with blood. 

The teeth are especially liable to decay soon after their appearance ; the enamel has 
not then attained its maximum density. They should be watched and a dentist con- 
sulted as soon as any signs of decay are detected. 



106 PHYSIOLOGY AND HYGIENE 

so that it cannot do its work. It irritates the waUs of the 
stomach and causes inflammation. 

The body needs a certain amount of food daily. If we 
eat more than this we do not get stronger,' as the body can- 
not use it. We simply overtax the digestive and eliminating 
organs. Overeating makes people dull and lazy. They can- 
not work well ; they build up fat instead of muscle, and this 
fat is a burden, not a benefit, to them. They get their or- 
gans out of order and suffer from indigestion and biliousness. 

Further, we must not eat large amounts of one substance, 
but should divide our diet among several kinds of food, as 
meat, vegetables, bread, milk, fish, fruit. 

The habit of eating large amounts of sweets, as candy, 
cake, and pastry, is a bad one. The body does not need so 
much sugar. It cannot use it, and the organs get overworked 
and out of order. There is a very serious disease, known as 
diabetes, which sometimes is associated with eating much 
sweet food. This eating of sweet substances also takes away 
our appetite for other foods which are necessary. 

The amount of food which we need varies with the work 
which we do and tlie climate in which we live. Men who 
work hard all day need more food than those who rest or 
loaf. In cold weather or in cold climates people need more 
food than in warm. The cold air tends to remove more heat 
from the body, and this loss has to be made up for by more 
food. The Eskimos, who live in the North, eat tremendous 
amounts of food, often as much as fifteen pounds a day. 

Mealtime. Eating between meals. In order that we may 
not overburden the digestive organs we divide our food into 
meals. It is best in temperate zones to take three meals a 
day, at intervals of about five or six hours— say breakfast at 
seven, lunch or dinner from twelve to one, dinner or supper 
at six. Between these meals one should not eat, as the 
digestive organs, like the body itself, need some time to rest. 



THE NUTRITION OF THE BODY 107 

A man should not eat heartily within one or two hours of 
bedtime, as the function of digestion is less active during sleep. 

He should not do hard work with his muscles or with his 
brain directly after a meal, as this exercise takes the blood 
away from the digestive organs, where it is needed. 

When a man comes in tired, it is a bad plan for him to 
eat heartily at once. In his fatigued condition the functions 
of digestion will not respond to the call upon them. 

Finally, we must avoid all substances which irritate or 
injure the digestive organs or disturb their function. 

Relishes. The spices— pepper, curry, and similar sub- 
stances—which are added to foods to make them appetizing 
are frequently irritating to the membrane of the stomach. 
The healthy man has a good appetite to make him relish his 
food, and needs no extra relishes. If, however, he gets used 
to having his food highly spiced, he becomes dependent upon 
these additions and the feeling of warmth which they cause 
in the stomach. He thus has to continue irritating his 
stomach and liver to keep up an appetite. 

Alcohol. Prominent among these substances which may 
irritate and injure the digestive organs are the beverages 
known as alcoholic liquors. Alcohol is a distinct irritant of 
tissue. If it be applied to the tongue it causes a burning 
sensation. It does the same thing when it touches the 
mucous membrane of the stomach. This irritation, where it 
is often repeated or severe, causes disorder and injury of the 
stomach. The irritated cells pour forth an excessive secre- 
tion, and become in time, if the irritation is kept up, inca- 
pable of performing their ordinary function.^ 

1 CMttendeii (American Joiimal of the Medical Sciences, vol. cxi.; American Journal 
of Physiology, vol. 1.) has made careful experiments upon the effect of varying amounts 
of alcohol upon gastric digestion. He finds, in digestion experiments made with mix- 
tures of digestive juice outside the body, that even small amounts of alcohol retard di- 
gestion. The same amounts cause a sliglit increase in the secretion of gastric juice 
when taken into the body. Tlie retardation effects and the secretion effects practically 
ijeutralize each other, as regards the total effect of alcohol upon gastric digestion. 



108 PHYSIOLOGY AND HYGIENE 

The harmful action of alcohol upon the digestive organs 
does not stop with the stomach. The liver, which purifies the 
blood flowing from the alimentary tract, has this irritant 
substance passing through its cells. Where this irritation is 
long continued there is reason to believe that the cells are 
injured : the liver becomes less able to perform its functions. 
Habitual drinkers not infrequently suffer from an incurable 
disease known as cirrhosis of the liver, of w^hicli the alcohol 
is in all probability to some extent a cause. 

Another practice which is apt to injure the digestive organs 
is taking hot or cold substances. Very hot substances cause 
inflammation of the mucous membranes of the mouth, esoph- 
agus, and stomach. 

Drinking much ice water without food irritates the stom- 
ach walls and makes one liable to indigestion. Drinking it 
with food often benumbs the cells, and thus delays the secre- 
tion of gastric juice and digestion. If one drinks ice water 
he should take simply a few sips at a time, as this small 
amount is warmed by the body almost as soon as it reaches 
the stomach. 

The drinking of large amounts of liquid is apt to stretch 
the stomach and make it less able to perform its functions. 
Thus, beer drinkers often have stomachs which are stretched 
much beyond their natural size. Such stomachs cannot, as a 
rule, digest food or pass it on to the intestines for absorption 
so w^ell as normal stomachs. 

Tobacco. Smoking is very apt to set up an irritation of 
the stomach and a disordered state of the secretions. This is 
due in part to the large amounts of saliva and mucus swal- 
lowed, and in part to the systemic action of the poison. 
The tobacco often seems to relieve the desire for food. This 
it does by benumbing the nerve sensibility upon which the 
sensation of hunger depends. By such action it impairs 
the appetite. 



THE NUTRITION OF THE BODY 109 

Chewing gum. The habit of chewing gum as a rule is 
one to be avoided. This practice calls forth an excessive 
secretion of saliva. This saliva is swallowed, and either 
keeps the stomach in a constant state of excitation or hinders 
the activity of the acid juices there. 



DEMONSTRATIONS AND EXPERIMENTS 

A good object lesson in regard to the needs of mastication, and to the 
adaptation of the teeth and jaws for different kinds of food, may be ob- 
tained by the study of the method of mastication, and the teeth and jaws, 
of various animals. 

A carnivorous (flesh-eating) animal, as the dog, seizes his meat and 
swallows it with but little chewing. A herbivorous (vegetable-feeding) 
animal, as the horse, chews his food for a long time, with a lateral as 
well as an up-and-down movement of the jaw. This suggests that 
vegetable foods are less easy to digest and need more breaking up and 
mixture with saliva than animal food ; and this is true of uncooked vege- 
table food, oats, gi-ass, etc. If you look at the jaw of the horse or cow you 
will see that its articulation allows of a lateral motion, while that of the 
dog allows only a hinge (up-and-down) motion. This is to enable the 
horse to grind his food thoroughly. 

The teeth of the carnivora will be seen to be adapted for tearing 
and cutting, even the molars having sharp edges, and closing past each 
other like the blades of a pair of scissors. 

The teeth of the herbivora will be seen to be fitted for grinding, the 
molars having rough, flat surfaces. These teeth, like an emery wheel, 
though they grind other things smooth, are themselves always rough. 
That is because they are formed of two substances, which wear away at 
different rates, so that an uneven surface is always left. 

If we now examine our own teeth and jaws we shall see, first, that we 
have both the cutting teeth of the carnivora and the grinders of the 
herbivora ; second, that our jaws allow of both the up-and-down and the 
lateral motion ; so that we are fitted for both the animal and vegetable 
diet. 

It is noticeable that among civilized nations the teeth are becoming 
less sound and vigorous. This is partly due to the fact that with the 
use of cooked food, food already ground and softened, there is less use 



110 PHYSIOLOGY AND HYGIENE 

for the teeth, and so, according to the law of evolution, they, as super- 
fluous organs, are tending to disappear. 

MASTICATION AND DEGLUTITION 

1. Chew and swallow slowly some food substance. 

Note how the different teeth act in the mastication, how the tongue 
and cheek muscles help in the process. 

Note that swallowing begins as a voluntary act, but that the food once 
started is beyond control. 

2. Note where the skin ends on the lips and where the mucous 
membrane begins. 

3. Wipe the tongue dry and place sugar upon it. At fii-st there is 
no taste, as the sugar has to be dissolved to affect the taste organs. 

4. Look into a boy's mouth and wipe the part under the tongue 
di'y. As you look a drop of saliva will collect. 

III. DIGESTION AND ABSORPTION 

We have obtained an idea of tlie nature of the food with 
which the body must be supplied, and of the organs by which 
this food is digested aud made ready for assimilation by the 
tissues. We must now endeavor to trace this food from its 
entrance into the alimentary canal to its destination where it 
appears transformed into tissues, muscle, flesh, and bones. 

Salivary digestion (Experiment 13, p. 124). Digestion of 
the food begins in the mouth, under the action of the saliva. 
The saliva is an alkaline fluid which contains a ferment 
called pfi/alin (Greek j^f^fff^o)}, ^^ saliva"). This ptyalin has 
the power at the temperature of the body of converting- 
starch, whicli cannot be absorbed through the membrane of 
the alimentary canal, into sugar which can be absorbed. 
Digestion of the starch of bread or vegetables therefore 
begins when such food has been mixed with the saliva. 

You can illustrate this digestion by holding in the mouth 
a little starch paste (see Experiment 13, p. 124) and noting 
the sweet taste which develops in a short time. 



THE NUTRITION OF THE BODY 111 

The proteids and fats are not acted upon by the saliva. 

Digestive ferments. These ferments, of which ptyalin is 
an example, are very important agents in digestion. They 
are chemical products of the gland cells which have the 
power of bringing about changes in the food substances with- 
out themselves being used up in the process.^ Tliere are 
other forms of ferments, of which the yeast cells and bac- 
teria are examples, which are alive. They are called organized 
ferments. In distinction from these the chemical ferments 
are known as unorganized ferments. 

Digestion in the stomach (Experiment 14, p. 125). The food 
enters the stomach as a soft mass mixed with the alkaline 
saliva. Here it is mixed with the digestive secretion of the 
stomach known as the gastric juice (Greek gaster, '^ stomach")- 

This juice secreted by the gastric glands upon the stimula- 
tion of the food contains an acid, hydrochloric acid, and two 
ferments, pepsin (Greek peptein, " to digest ") and rennin. It 
acts principally upon proteids. The acid and pepsin acting 
together convert the native albumins of meat and vege- 
tables to albumoses and peptones^ forms of proteid which 
can be absorbed. The rennin coagulates casein, the proteid 
of milk. 

The action of the saliva upon starch is stopped by the acid 
gastric juice. The carbohydrates and fats are not digested 
by the gastric juice, which does, however, digest away the 
albuminous envelope of the fat cells, and thus by freeing the 
fat facilitates its digestion later. 

Digestion in the intestine. The food, after remaining in the 
stomach until proteid digestion is suf&cieiitly advanced, is 
propelled into the intestine. This period is from three to six 

1 The most important digestive ferments are the ptyalin of the saliva and the amy- 
lopsin of the pancreatic juice, which convert starch to sugar; the pepsin of the gastric 
juice and the trypsin of the pancreatic juice, which convert albumins to albumoses 
and peptones; the rennin, which coagulates (curdles) milk; the ferment of the intes- 
tinal juice, which inverts cane sugar. 



112 PHYSIOLOGY AND HYGIENE 

hours with a full meal. Practically but little absorption 
occurs in the stomach. 

The digested gastric contents, or chyme, enters the duode- 
num, and is there acted upon by the pancreatic juice and bile 
and the secretions of the intestinal glands (see p. 128). 

The pancreatic juice is a watery alkaline fluid containing 
sodium carbonate and three ferments, amijlopsin, tnjpsin, and 
steapsin. 

The amylopsin digests starch to sugar. The starch foods 
which have escaped the salivary action, or those which have 
not been completely converted to glucose, are here fully 
digested. 

The trypsin^ like the pepsin, digests proteids, but in an 
alkaline medium instead of an acid. The proteids which 
escape complete digestion in the stomach are finished here. 

The steapsin acts upon the fats, splitting the natural fat 
into fatty acid and glycerin. 

The intestinal juice from the small glands which lie in the 
walls of the membrane contains a ferment which inverts 
sugar ; that is, it turns the cane sugar which we eat to invert 
sugar ^ a sugar with smaller molecules, more suited for absorp- 
tion. 

With the action of the intestinal secretions the digestion of 
the food is completed. The native food substances have been 
converted to soluble forms with molecules small enough to 
pass the intestinal cells, the proteids to albumoses and pep- 
tones, the carbohydrates to invert sugar and dextrose 
(glucose). 

The fats have been brought into a finely divided state 
known as an emulsion, or broken up into fatty acids and 
formed into soap, in which forms they can be absorbed 
(Experiment 15, p. 125). 

Absorption. The alimentary contents are thus prepared for 
absorption into the blood. This process occurs through the 



THE NUTRITION OF THE BODY 113 

medium of the epithelial cells and the villi of the intestinal 
mucous membrane. The molecules of these substances 
formed as a result of digestion are small enough to be 
passed through these intestinal cells. Thus, during and after 
digestion these sugars, peptones, and fat products, the min- 
eral salts and water, are taken up by the cells and transferred 
to the blood and lymphatics. Some of the products are 
passed unchanged into the blood, others are elaborated into 
different substances by the cells through which they are 
passed; but the essential food principles, proteids, carbo- 
hydrates, and fats, with water and inorganic salts, all get 
into the blood in some form.^ 

The villi in absorption. The structures described as villi 
are particularly active in this process of absorption. The 
epithelial cells of the villus pass the products through and 
discharge them into the blood vessels and the central lacteal. 
During digestion these vessels are loaded with these products, 
which they bear away to the blood. In this process the in- 
testinal cells act like porters unloading a ship into railroad 
cars. The merchandise is taken from the ship (the intestine) 
and put upon the railroad (the blood vessels), which dis- 
tributes it over the country (the body). After absorption the 
food is collected by two sets of vessels, the lymphatic vessels 
and the portal vein. The food collected by the lymphatics 
is called the chyle. It is collected together into a large vessel, 
the thoracic duct, and discharged from this into the blood. 

The food collected by the blood vessels of the villi and the 
intestinal walls is discharged into a large vein, the portal vein. 
This vein carries it to the large gland already mentioned, the 
liver. Here it is, roughly speaking, filtered and further 
elaborated by the liver cells, its useful parts poured into the 
blood of the general circulation, while its harmful or poi- 

1 The physical processes involved in absorption are imbibition and osmosis, in all 
probability. Osmosis is described on page 120. See also page 126. 



114 



PHYSIOLOGY AND HYGIENE 



sonous elements are destroyed or turned aside into the bile 
for elimination from the sj'stem. 

Structure of the liver. In structure the liver consists of 
cubical epithelial cells compactly arranged in bundles known 
as lobules (small lobes). Each lobule is built up with connec- 





Liver. 

a, b, c, artery, veiTi, and bile duct ; y b, gall bladder. 

tive tissue in which run numerous blood vessels from the 
portal vein. These vessels run between the cells in the 
center of the lobule. By these cells harmful substances or 
substances reserved for special purposes are taken from the 
portal blood. The purified food in the portal blood is then 
carried on to the blood stream which feeds the body tissues 
by the hepatic vein. The liver separates from this blood 
waste products which the blood has taken up in the body, as 
well as the waste food; for instance, the waste coloring 
matter of the blood corpuscles, and the waste nitrogen prod- 
ucts which result from the breaking down of the proteid 
tissue substances. Some of these waste products are ex- 
creted in the bile. Others, as urea, are poured into the 
blood and excreted by the kidneys. 



THE NUTRITION OF THE BODY 



115 



The liver cells also store up some of the carbohydrate food 
in the form of glycogen. 

IV. CIRCULATION AND ASSIMILATION 

The blood and lymph. The food which has been digested, 
absorbed, and purified has to be borne from the intestines 
and liver to the tissues which it is to nourish. Also, the 
tissues thus nourished have to be provided with free oxy- 
gen from the lungs for their combustion to form energy. 
Thirdly, tlie waste products of this combustion of the tissues 
have to be carried away 
and disposed of. This 
carrying of the food and 
waste of the body is the 
function of the hlood and 
tlie lymph. 

The hlood is a fluid sub- 
stance of red color which 
circulates throughout ^' | y J] 
the body. It consists of 
a watery substance, the 
plasma, in which are sus- ^^^ corpuscles. 

' r, corpnsfle (full view) ; ?•', corpiiscles (side \'iew) ; 

pended great numbers ''". coi-puscles in rolls (rouleaux) ; c, erenated cor- 

of small semisolid bod- 
ies, the corpuscles. These corpuscles are of three kinds, the 
red corpuscles, the white corpuscles, and the blood plaques. 
The red corpuscles are small circular biconcave disks, like 
coins, with their upper and lower surfaces hollowed out. 
The corpuscles give the red color to the blood. Each cor- 
puscle has a diameter of from six to nine micromillimeters— 
about 3yVo c>f an inch. They are very numerous— about five 
million to one cubic millimeter of blood. If a drop of blood 
be spread upon a glass slide and looked at under the micro- 
scope, these corpuscles may be seen lying free or in rolls. 

HEWES, P. & H,— 8 





116 PHYSIOLOGY AND HYGIENE 

In structure the corpuscle consists of an elastic protoplasm, 
or stroma, in which is set the red coloring matter, hemoglobin^ 
much as the color is set in the glass of a colored marble. 
This hemoglobin is a very important substance which carries 
the oxygen from the lungs to the cells. In blood it is always 

combined with some of this 
oxygen, and is thus oxyhemo- 
globin. 

White corpuscles. ^he ivh ite corpuscles, or leu- 

cocytes (Greek ZeitA'os, ''white," 
and I'utos, " cell "), are colorless bodies of many sizes, but 
mostly larger than the red corpuscles. They are less numer- 
ous than the red, numbering about eight thousand to a cubic 
millimeter, or one to six hundred reds. 

These ichite corpuscles are really single cells, which are free 
in the blood. . In them we have a chance to observe the 
character of the living cell, which is the unit of structure in 
all the tissues. 

Each corpuscle consists of a nucleus surrounded by pro- 
toplasm. The whole cell is enveloped in a cell membrane. 
The nucleus is more dense in substance than the protoplasm. 
Its form may be round or horseshoe shape or still more 
irregular. The protoplasm is a colorless, translucent sub- 
stance. It is often filled with fine granules. 

Like all cells at some period of their existence, these 
corpuscles are alive. They take up and discharge new sub- 
stances to and from the plasma, divide and form new cells, 
and many of them have the power of amoeboid motion (see 
p. 17). Owing to this power of motion they may take any 
shape, but as a rule they appear spherical in the blood. 

The hlood plaques are very small, protoplasmic, disk-shaped 
bodies. 

Coagulation (Latin coagulare, "to curdle"). When the 
blood is taken from the body or exposed to the air for a few 



THE NUTRITION OP THE BODY 117 

minutes it forms a jellylike mass called a dot This pro- 
cess of clot formation is known as coagulation. The coag- 
ulation is due to the formation of fine elastic threads in a 
thick network in the blood. This threadlike substance is 
called /&>'»?. In thus collecting it forms a firm mass which 
collects the corpuscles in its meshes. The fluid parts of the 
blood, the serum, may be squeezed out and separated. 

Coagulation is a very useful process in stopping the bleed- 
ing from a wound by plugging up the opening in the ves- 
sels with the clot. 

The fibrin is formed from substances in the plasma by the 
action of a ferment. The removal of this fibrin from the 
plasma leaves the serum (Experiments 20, 21, pp. 128, 129). 

The serum (Latin for ^' whey "), which is the plasma of the 
blood minus the fibrin, consists of water with mineral salts, 
proteid substances, and certain other materials in solution. 
The proteids of the serum are two in number, albumin (Latin 
alhus, ^' white") and gloduUn, substances like the proteid of 
white of egg (Experiment 23, p. 129). 

The salts of blood are chiefly chlorides and carbonates of 
sodium and potassium and phosphates of magnesium and 
calcium. They are contained in both the plasma and the 
corpuscles. The corpuscles contain iron combined in the 
hemoglobin. 

The food substances which are absorbed are carried in 
the blood in solution and in suspension. We thus have in 
the serum of blood after a meal proteid, carbohydrate, and 
fat substances which have been absorbed and are on the 
way to the tissues, also lime salts, phosphates, and other 
minerals going to the bones and brain and other tissues 
which need them. 

The circulation of the blood. Thus, to carry the food and 
oxygen to the tissues and the waste away from them the 
blood is circulated through all parts of the body. This pro- 



118 PHYSIOLOGY AND HYGIENE 

cess is called the circulation (Latin circulare, " to encompass ") 
of tlie Mood. 

For the carrying out of this process an organ or series of 
organs is provided, the circulatory system. This system con- 
sists of the heart and the blood vessels. 

The heart is a muscular pump which keeps the blood ever 
flowing. 

The hlood vessels are muscular and elastic tubes which con- 
duct the blood over the body. Those which take the blood 
filled with food and oxygen to the tissues from the heart 
and lungs are called arteries (Greek aer, "air," and terehi, 
" to keep." It was formerly thought that arteries carried 
air, as they were found empty of blood after death). Those 
which return the blood from the tissues with the waste 
materials are called the veins (Latin venire, "to proceed"). 

The arteries when they reach the tissue which they supply 
divide into fine tubes called capiUaries (Latin capiUus, "a 
hair "), which permeate the tissue and come together again in 
veins. 

The food and oxygen in this arterial blood, during the 
passage of the blood through the capillaries, pass through 
the walls of the capillaries into the lymph (Latin lympha, 
" water"), which takes them to the cells. Some of the waste 
products from the tissues collected by this same lymph pass 
back through the capillary walls to the blood, just as in the 
experiment (p. 126) with the egg some of the water passes 
into the egg and some of the egg albumin into the water. 
The blood then goes on to the veins and through them, de- 
prived of its food elements and filled with waste. 

The veins bear this blood back to the heart, whence it is 
pumped to the excretory organs, as the kidneys, where it 
gets rid of the waste products, and to the lungs and ali- 
mentary tract, where it takes up a new supply of food and 
oxygen, and so on round the body again. 



THE NUTRITION OF THE BODY 



119 



The blood which is going to the tissues filled with a supply 
of oxygen and food is called arterial hlood; it is bright scar- 
let in color. That which is returning in the veins to the heart 
from tlie tissues is called venous hlood; it is of a dark purple 
color. 

This circulation of the blood can be studied in the web of 
a frog's foot. If we look at this web under the microscope 




Blood in capillaries in tissue. 



we see fine tubes dividing into still finer ones, all filled with 
blood. Through the larger tubes the blood comes, flowing 
into the smaller. In the small tubes the flow is slow, the 
corpuscles going in single file. Collecting the blood from 
the fine capillary tubes, we see small veins of blue color. 

The lymph. The blood flows in tubes, and thns does not 
get directly to the cells of the tissues, except the cells of the 
vessel walls. Its nutritious products are brought to the cells 
by what is known as the lymph. 



120 PHYSIOLOGY AND HYGIENE 

The lymph is a watery liquid which fills the interstices of 
the tissue among the cells and about the capillaries. 

The nutritious substances of the blood pass through the 
capillary walls into this lymph. The lymph gives them up to 
the cells which are bathed in it. At the same time the lymph 
collects the waste from the cells and returns it to the blood. 

The process of interchange between the two fluids, the blood 
and the lymph, through a membrane which separates them, is 
called osmosis (Greek osmos, " impulse ")• Where this process 
occurs we have two fluids of different densities separated by a 
membrane, as the intestinal mucous membrane, or the walls 
of a blood capillar}'; that is, we have, as in Experiment 16, 
page 126, on one side of the membrane a dense fluid, white 
of egg for instance, and on the other a thin fluid, water. 
When osmosis occurs these fluids interchange their sub- 
stance, the dense fluid (the egg white) giving up its heavier 
constituent to the w^ater, and tlie thin fluid (water) giving 
up its lighter constituent (the water itself) to the egg, so 
that they tend to become equally dense, the egg becoming 
watery and the water becoming heavier. 

So in the circulation the blood gives up food substances, 
salts, and water ; the lymph gives up waste substances. The 
same process is active in the absorption from the small intes- 
tine. Here the intestinal contents on one side of the mem- 
brane give up food to the blood on the other side and take 
up water from the blood, so that the intestinal contents 
become more liquid, while the blood becomes more concen- 
trated. 

The lymphatics. In this interchange between the blood and 
the lymph in the tissues the blood gives up a larger amount 
of fluid than it takes back. The amount of lymph in the 
tissues would tend therefore to increase all the time. This 
excess of lymph, however, is collected and carried away from 
the tissues by a set of vessels known as the lymphatics. 



THE NUTRITION OF THE BODY 121 

These vessels drain all the lymph spaces in the tissues. 
They collect into larger vessels and finally empty into the 
large veins, so that the lymph and its waste products all get 
back to the blood. 

The lacteals, which collect some of the food absorbed from 
the intestine, belong to this system of lymphatics. 



DEMONSTRATIONS AND EXPERIMENTS 



1. Reaction. Acids and alkalis. 

There are certain chemical substances which are known as acids. 
These substances can be tested for by using blue litmus paper. An 
acid or any substance which contains an acid turns blue litmus red. 
This test is the indication of the fact that a substance is an acid or 
contains an acid. The substance which gives this test is said to have an 
acid reaction. The gastric juice gives this test, as it contains hydro- 
chloric acid. 

Another set of chemical substances are known as alkalis. These 
substances turn red litmus paper blue, or yellow turmeric paper red. 
The saliva, the pancreatic juice, the blood, turn red litmus blue, as they 
are alkaline in reaction (contain alkalis). 

Some substances do not change the color of litmus. They are neu- 
tral in reaction. Salt and water are such substances. 

Test some blue litmus with hydrochloric acid ; with sodic hydrate ; 
with saliva. Test some red litmus with the same substances. 

2. Solution. 

When you add sugar or salt to water and shake the mixture, the solids 
disappear ; the mixture remains clear. Such a mixture is known a^ a 
solution. The substances which thus disappear are said to be soluble 
in water. This process of solution occurs in the mouth, and stomach, 
and intestines. The sugar or salt eaten is dissolved there as in the test 
tube. Other substances, as starch and hard-boiled egg, are insolu- 
ble in water. They do not disappear in water or make a clear mixture. 
These substances have to be changed in the body (by digestion) to 
soluble substances. 

Try shaking each of the above substances in water to illustrate the 
above statements. 



122 PHYSIOLOGY AND HYGIENE 

3. PrecipitateSo 

When two substances are mixed they may form a third substance. 

Add some of a nitrate-of -silver solution to a solution of salt (sodium 
chloride). Note the formation of a third substance, a white powder 
which sinks in the liquid (chloride of silver). 

This third substance is insoluble, while the first two substances were 
soluble. Such an insoluble substance formed by adding any chemical 
to a second chemical in solution is called a precipitate. 

EXPERIMENTS UPON FOODS 

A clearer understanding of the nature and composition of the vari- 
ous food substances will be achieved if the pupil familiarizes himself 
with the tests for the chief constituent substances of the foods— proteids, 
carbohydrates (starches and sugars), fats, mineral salts. 

4. Demonstration of the adaptability of organic food for burning 
with charring. 

One of the important characteristics of organic foods in distinction 
from inorganic is their adaptability for burning. 

Place meat or any vegetable upon a hot fire. They will char and 
burn up. This is due to their organic (carbon-containing) character. 

Place a rock or a lump of salt upon a fire. These will not char, as 
they contain no carbon, or burn, as they contain no substance which, 
like the carbon of organic foods, unites with the oxygen at 'the ordinary 
fire heat. 

5. Tests for proteid substances. 

A fairly pure proteid substance which is easy to experiment with is 
white of egg. Separate the whites of two or three eggs. Stir this egg 
albumin in a pint of water. Filter the mixture. With the fluid which 
has been filtered perform the following tests for proteids. These tests 
can be obtained upon the proteid substances of any food, as meat, corn, 
wheat, milk, etc. 

(a) To a little of the solution in the test tube add some nitric acid. 
Note what occurs. Then add a little ammonia (ammonic hydrate) 
to the mixture. Note the color which appears. This is a test for 
proteid substances. (Xanthoproteic test). 

(&) To some of the solution add some sodic hydrate and one or two 
drops of a one per cent solution of copper sulphate. Note the color 
which results. (Biuret test for proteid.) 

(c) Heat some of the solution of egg albumin. The precipitate which 
appears is the albumin. (If no precipitate appears add one drop of dilute 



J 



THE NUTRITION OF THE BODY 123 

acetic acid and heat again.) This is a test for a special kind of proteid, 
not all i^roteids. 

6. How do these tests react upon meat juice? 

7. Tests for carbohydrates. Starch. 

(a) Rub up some corn starch with a little cold water. Add to this a 
gill of boiling-hot water. (This mixture is called starch paste.) To some 
of the milky mixture (cool) add a drop of tincture of iodine or of Lugol's 
solution. Note the color which appears. This test for starch may be 
applied to the starch of various foods, as potatoes, wheat, flour, fruit. 

(&) Grate a potato into a glass of water. A white powdery substance 
which falls to the bottom of the glass is the starch of the potato. 

8. Test for grape sugar (Fehling's test). 
Dissolve a small amount of grape sugar in water. 

Heat a small quantity of Fehling's solution in a test tube. To this 
hot liquid add an equal amount of the sugar solution. Note what 
occm's. Heat again. Note result, if any. 

9. Tests for fats. 

(«) Shake a small piece of butter (the fat from milk) or a little sweet 
oil (fat from olives) up with ether. What happens? Filter, and allow 
the ether to evaporate. 

(&) Mix some ether with a tablespoonful of flaxseed meal. Let stand 
for fifteen minutes. Shake and filter, and allow ether to evaporate. 

What is left in the evaporating dish in («) and (&) ? Add a little water 
to this residue. What do you observe? 

Perform the same experiment with milk. 

(c) Rub some flaxseed meal upon paper. Observe result. 

10. To demonstrate the amount of water in foods. 

(«) Weigh a piece of meat, as fresh beef. Set aside in a warm, dry 
place for twenty-four hours. Weigh again. The loss of weight is due 
principally to the water which has evaporated. Weigh at the end of 
forty-eight hours ; seventy-two hours. 

(b) Remove the peel from an apple or potato. Weigh the peeled fruit 
and allow it to dry. Note loss of water from day to day. 

11. Tests for mineral substances in foods. 

(a) Heat and fuse some flour or meat or milk in a crucible until heat- 
ing causes no further change. The residue left (the ash) represents 
the mineral matter of the food, which, as you know, unlike the organic 
matter, does not burn. 

(6) Dissolve some of the ash in water. Filter. To the filtrate (the 
watery solution) add some nitrate of silver. What appears? 

Part of the precipitate which occurs is due to the salt, sodium chloride, 



124 PHYSIOLOGY AND HYGIENE 

in the food, which, as in Experiment 3, page 122, forms, with the silver 
salt, the insoluble silver chloride. 

12. Tests to show the constituents of milk. 

(a) Allow milk to stand for some time. The thick layer which col- 
lects on the surface, the cream, consists principally of the fat which is 
contained in the milk. 

(b) Test for proteid by general tests for proteids given on page 122. 

Heat some milk and add some acetic acid. A thick, flocculent sub- 
stance, known as curd, which consists of the proteid (casein) contained 
in milk, is formed. The whey is the liquid left after removal of the 
curd. If both the cream and the curd are removed from the milk it 
still contains a carbohydrate substance, lactose or milk sugar. 

(c) If a little whey is boiled with Fehling's solution we get a yellow- 
ish-red substance. This red substance is due to the action of the sugar 
(milk sugar) in the milk upon the copper, and proves that sugar is pres- 
ent in the whey. 

Shake some milk with ether, filter and evaporate. Note the fatty 
residue, which is the fat of the milk. 

We can thus find and separate proteids, fats, and carbohydrate sub- 
stances in milk. 

Evaporate some milk by boiling. The loss in weight is due princi- 
pally to the loss of water. The residue is the solid substance of milk. 
This experiment shows how great a part of milk is made up of water. 
Fuse the residue in a crucible. The ash or mineral constituents re- 
main. Test the ash as in Experiment 11. Test for phosphates as in 
Experiment 7, page 62. 

EXPERIMENTS TO ILLUSTRATE DIGESTION 

13. Digestive action of saliva, illustrating digestion of starch. 

(a) Place a little starch paste (Experiment 7, a, p. 123) on the tongue. 
In a short time a sweet taste will develop. This sweet taste is due 
to the sugar which is formed from the starch in the digestion by saliva. 

(&) Add some starch to water. Note that the liquid mixture is 
cloudy. The starch does not disappear. Add some sugar to water and 
shake. Note that the sugar disappears. The liquid mixture is clear; 
that is, the sugar is more soluble in water than is starch. This shows 
one reason for the usefulness of the change of starch to sugar by diges- 
tion. This is not, however, the only reason. The fact that the grape 
sugar (glucose) molecule is smaller than that of the starch and can 
better pass through the intestinal membrane (absorb) is the chief reason. 



THE NUTRITION OF THE BODY 125 

(c) Chew some paraffin. Collect the saliva which flows in abun- 
dance into the mouth. Make some starch paste. Test with Fehling's 
test to prove no sugar is present. Add some of the saliva to some 
starch paste another portion of which has given the blue color with 
iodine. Put in a warm place (over a radiator). In five minutes 
perform Fehling's test. How did the sugar arrive? Twelve hours 
later perform the iodine test. The blue color will not appear, and a red 
color, or perhaps no change of color, vnll appear. The starch has all 
been turned to sugar or to other substances. 

This experiment illustrates what occurs to starch in digestion in the 
body. 

{d) Take some dry corn starch (uncooked starch) and mix with 
saliva. Test this mixture for sugar in five minutes. Is the effect of 
the saliva the same upon this uncooked starch as upon the cooked 
starch (the starch paste) ? 

The digestion of the starch in wheat, potato, fruits, etc., is carried 
on by the pancreatic juice in the same manner as by the saliva. The 
pancreatic juice, however, digests uncooked starch also. 

14. Digestion by the gastric juice, illustrating digestion of proteids. 
Mark two one-ounce bottles. Fill 1 with water ; fill 2 with a mixture 

of hydrochloric acid and pepsin made up as follows : hydrochloric acid, 
6 cc. ; water, 1,000 cc. ; pepsin, 10 gm. This represents an artificial 
gastric juice except for the absence of rennin. 

Place a small piece of hard-boiled egg or fibrin in each bottle, and 
keep in a warm place, as over a steam radiator (not above the body 
heat). 

Note that the egg remains unchanged in the first (water) bottle. 

In the second it disappears, is digested. The digestion of proteids 
— the albumin of eggs, meats, grain, etc. — in the body occurs in this 
manner. 

Here, as with the digestion of starch by saliva, ^the digestion often 
forms a soluble substance from an insoluble one. Witness the coagulated 
egg albumin in the above experiment. But the proteid substance is often 
soluble in the first place, in raw eggs, milk, etc., and the main object 
of the digestion is to break up non-absorbable proteids so that they 
will pass through the animal membranes. 

Proteids are digested in the intestine by the pancreatic juice, as in the 
stomach by the gastric juice. 

15. Digestion of fats. 

(a) Place some butter in some water kept at the body heat (98.6° F. ). 
What occurs ? Shake up the water and fat, or some olive oil and water. 



126 PHYSIOLOGY AND HYGIENE 

Do they mix? Place under the microscope a drop of the water which 
has been thus shaken. Can you distinguish the fat globules ? 

(h) Shake up some olive oil with a solution of sodic hydrate. Does 
any mixture of the substances occur? 

Look at a drop of this mixture under the microscope. Can you dis- 
tinguish the fat globules here as in the water? 

The mixtui-e of the fat and the alkali forms an emulsion. The two 
substances do not tend to separate after shaking, as in the case of the 
oil and water. The fat in an emulsion is so finely divided that you can- 
not see the globules. 

(c) Mix some olive oil and sodic hydrate, and boil. Describe the mix- 
ture which forms. This is soap. 

The processes illustrate in a rough way the digestion of fats in the 
body. The fat is melted in the stomach. In the intestine it is broken 
up and forms an emulsion with the alkaline fluids there, the pancreatic 
juice, bile, etc., some of the fat here being formed into soap. 

01) Obtain some bile. Test the reaction. Add some oil to bile and 
shake. Is an emulsion formed? Examine mixture under microscope. 

EXPERIMENTS TO ILLUSTRATE ABSORPTION 

16. Absorption by osmosis can be represented by the following ex- 
periment : 

Make a hole about half an inch in diameter in the large end of an 
egg by breaking through the shell and cutting the outer shell membrane. 
The air space between the inner and outer shell membranes is thus 
opened. Then immerse the egg in a glass of water, with the open 
end upward and the lower end held in place by a ring support (a napkin 
ring). The albumin of the egg white is thus separated from the water 
by the inner shell membrane. Through this membrane osmosis occurs 
readily, the water passing inward and the albumin outward, so that the 
density of the egg contents and that of the water outside tend to approach 
each other. The water goes in, however, more rapidly than the albumin 
comes out, and as a result the membrane becomes more distended, bulges 
out through the hole, and finally bursts. This bulging demonstrates 
that the water is going through the membrane.! 

Obtain some sacs made from animal membranes. (The sausage 
covers made from pigs' intestine are good for this purpose.) 

Into a small sac made of the sausage skin pour a solution of grape 

1 This and several other experiments are taken from Dr. H. P. Bowditeh's Hints 
for Teachers of Physiology. 



THE NUTRITION OF THE BODY 



127 



sugar. Suspend the sac in a two-ounce beaker of distilled water. After 
a few hours test the water in the beaker for grape sugar. (Fehling's 
test.) 

Perform the same experiment with a mixture of starch and water in 
the sac. Test water in beaker for starch. (Iodine test.) 

Note that the sugar passes through the membrane, the starch does 
not. Starch therefore has to be digested to sugar to absorb. 

Perform the same experiment with a solution of egg albumin. Test 
water for proteids. Perform the experiment with a solution of salt 
(sodium chloride). Test water for salt by adding nitrate of silver. 

These experiments represent in a rough way one part of the process 
of absorption. The sausage skin represents the intestinal membrane. 
The sugar, the salt, etc., pass through this into the water, as in the 
body they pass through into the blood. 

In the body, however, the cells pf the membrane are alive and trans- 
form these substances as they pass through. In this dead membrane 
osmosis is the only active force present. 

17. Physical methods of absorption. 

Absorption occurs partly as a physical process, diffusion, but partly 
by a specific action of the living cells. The physical processes can 
be illustrated by the following experiments : 

(a) Place a few pieces of glass tubing of different sizes in a glass of 
water, and note that the water rises higher in the tubes than in the 
glass, and highest in the small tubes. This represents the process of 
capillary imbibition, which is a part of the process of absorption in the 
intestine. The same thing can be illustrated by placing a piece of filter 
paper in water colored with aniline blue. 

(h) The process of perspiration is an example of imbibition. 

18. Fill out the following table with the results obtained by ap- 
plying these common tests which have been described for proteids, 
carbohydrates, and fats to the food substances given. 



Test. 

Heat 

Xanthoproteic 

Biuret 

Iodine 

Fehling's 

Solubility in ether 



Starch. 


Grape 
Sugar. 


Olive 

Oil 

(Fat). 









Egg 
Albu- 



Pep- 


Meat 


tone. 


Juice. 







128 PHYSIOLOGY AND HYGIENE 



DIGESTION BY THE PANCREATIC JUICE, ILLUSTRATING 
INTESTINAL DIGESTION 

19. Procure a fresh pancreas from a pig. Cut up finely and gi'ind 
with some fine sand in a mortar. 

To one ounce of the pancreas add four ounces of twenty-five per cent 
alcoliol, and let the mixture stand three days. Filter, and use the fil- 
trate for experiments. 

(a) Digestion of proteids by the pancreatic ferment (trypsin). To 
10 ce. of the pancreatic extract add twice that amount of one half 
per cent sodium carbonate in a test tube.l 

Into the tube place a small piece of coagulated white of egg or a 
piece of fibrin, and place mixture over a register or in any place where 
the temperature is about the body heat (98.6° to 100° F.). Note the 
gradual digestion of the proteid, which will, in time, disappear entirely. 

(6) Digestion of carbohydrates by the amylolytic ferment of the pan- 
creas. To 10 cc. of starch paste add an equal amount of one half per 
cent sodium carbonate, and then a few drops of the pancreatic extract, 
and warm the mixture. Note that the milky starch mixture becomes 
clear. 

This pancreatic ferment digests uncooked starch also, which the 
salivary ferment does not do. 

(c) Digestion of fats by the fat-splitting ferment of the pancreas. 
Carefully neutralize or make slightly alkaline a little of the pancreatic 
extract with the one half per cent solution of sodium carbonate. Add 
this mixture to 2 ec. of neutral olive oil to which a little blue litmus 
powder has been added, and stir the mixture. 

Set in warm place. Note the change in the blue color of the mix- 
ture to purple and pink, also later the formation of an emulsion. (The 
red color is due to the acid which is formed by the action of the ferment 
on the fat. 

EXPERIMENTS UPON THE BLOOD 

20. Obtain a half pint of fresh blood from the slaughter house. 
Allow it to stand in a wide-mouthed eight-ounce bottle. After a time 
a cup-shaped clot \rill form, adhering to the glass. Below it will be 
the nearly colorless serum. 

1 The pancreatic ferments act in an alkaline reaction, which is provided in the body 
by the sodium carbonate of the bile and pancreatic and intestinal jiiices. 



THE NUTRITION OF THE BODY 129 

21. Obtain a half pint of blood and whip it briskly with some small 
twigs. Fine threads of fibrin will collect upon the twigs. When 
the fibrin thus formed has been removed the blood will not coagulate 
upon standing. 

22. The coagulation of blood can be observed with but a few drops 
of blood, if the blood is kept in a moist chamber to prevent drying. 
Prick the finger, which has been washed in alcohol, with a bayonet- 
pointed needle which has been passed through a flame to sterilize (kill 
all bacteria upon) it. Collect a few drops of blood upon a small butter 
plate. Invert this over a saucer of water and cover with a tumbler. 
In a half hour or less the blood will form a jellylike clot. 

23. Test the blood serum (Experiment 20) for proteids. Heat test. 
Nitric acid and ammonia test (Xanthoproteic). 

Test for sugar with Fehling's test. 

Rub a little upon some paper. Does it appear to contain fat? 

24. Defibrinate some blood by whipping it. 
Pour off the defibrinated blood. Note its color. 

Shake this in a bottle with air. What change occurs in the blood? 

25. Corpuscles. 

Prick the finger. Take a drop of blood upon a cover slip. Drop 
this blood side downward upon a glass slide. Examine specimen with 
a microscope (500 diameters). 

Observe the red corpuscles. 

Observe the white corpuscles. Look for one in motion (amceboid 
motion). 

QUESTIONS 

I. What are the two objects fulfilled by the food? What causes the 
constant wasting in the body? How do we know what substances must 
be present in the food to supply the body needs? Name some of the 
elements contained in the body substances. 

II. In what form do we take the necessary nitrogen and carbon into 
the body? Why do we need compound substances for food? Give two 
objects accomplished by the use of organic foods. Mention some in- 
organic food substances. From what kingdoms of nature do most of 
our foods come directly? 

III. Name the three classes of organic food substances. Which of 
these substances is the principal constituent of the body tissues ? What 
foods contain proteid? What is the chief use of carbohydrates and 



130 PHYSIOLOGY AND HYGIENE 

fats in the body? What foods contain carbohydrates? What foods 
contain fat? 

IV. Can we live on any one of these three classes of food alone ? Upon 
which one? Is it best to live on one kind of food substance? In what 
forms do we take water into the body? In what way do we get our 
mineral salts, the lime salts, chlorine, sulphur, iron, etc. ? 

V. How can we tell how much food we need? What is the effect of 
hard work upon the need of food? Explain why we employ a mixed 
diet. How does the food get to the tissues of the body? (Name the 
several processes through which it must pass in this course.) 

VI. What is the object of digestion? What is the name of the di- 
gestive tract? Name the principal and accessory parts of this digestive 
system. What is a gland? What is the action of a gland called? In 
what does this process consist? 

VII. Describe the contents of the mouth. Describe the teeth. How 
are the teeth fashioned according to their fimction? What is the saliva? 
Describe mastication. Describe the act of swallowing. Is it voluntary 
or involuntary? What parts does the food pass through in getting to 
the stomach? 

VIII. What is the stomach? What is the lining of the stomach called? 
What structures lie in this membrane ? What is tlie intestine ? What 
is its length? What structures lie in or upon the membrane of the 
small intestine? Describe a villus. What is the function of the villi? 
What is a lacteal? What large external glands supply the intestine 
with secretions? 

IX. What is the bile? Is the bile an excretion? What use is it as a 
secretion? What is the use of the gall bladder? What is the pancreas? 
What does it secrete? In what part of the intestine is most of the food 
absorbed? Where is most of the water absorbed? 

X. What precautions in regard to the choice of food and the method 
of eating does the study of the organs of digestion suggest? Why do we 
cook food? Why do we have regular mealtimes? What are relishes? 
What is the effect upon the stomach of smoking? Is alcohol drinking 
likely to cause disorder of this organ ? 

XI. Describe salivary digestion. What class of food is digested by 
saliva? What is an unorganized ferment? Name the digestive fer- 
ment of the saliva ; of the gastric juice. What food is digested by the 
gastric juice? What foods are digested in the intestine? 

XII. What is the important digestive juice of the intestine? What 
other digestive secretions are found there ? What is the action of ren- 
nin? Where does absorption occur? Describe absorption in the villi. 



THE NUTRITION OF THE BODY 131 

XIII. Through what two channels is the absorbed food borne away to 
the general circulation ? Where is the food collected by the portal vein 
first carried! What occurs to the portal blood in the liver? Where does 
the food go from the liver? What becomes of the substances removed 
from the blood by the liver cells? What carries the food to the tissues? 

XIV. Describe the blood. What is the function of the red corpuscles ? 
Describe a leucocyte. What other functions has the blood besides 
bearing the food? Does the blood carry the food directly to the cells? 
What is coagulation? What is fibrin? What is the blood serum? 

XV. What is the circulatory system ? What becomes of the food when 
it reaches the capillaries? What is the difference between arterial and 
venous blood? Describe the lymph. Describe osmosis. What are the 
vessels which carry the lymph? Where is the waste collected by the 
lymph carried? Describe the course of the food from the mouth until 
it becomes a part of the tissue cells. What happens to the food 
in the cells? 

XVI. Illustrate by examples how the anatomy of an animal may sug- 
gest the nature of his food. Is the solution of the food the only object of 
digestion? What other factor besides the physical factor enters into 
absorption? How may a failure to brush the teeth affect the health of 
the stomach? 



HEWES, p. & H.— 9 



CHAPTER VI 

THE HYGIENE OF NUTRITION 

THE VALUE OF THE DIFFERENT FOODSTUFFS FOR 
NUTRITION— CONDIMENTS AND BEVERAGES 

WE have now studied the utilization of food in the body ; 
how it is taken in and distributed to the tissues, and 
the changes which it undergoes in the process of metabolism. 
We understand why we eat food, and why we use the special 
substances which we do, the organic products, water, and 
salts. 

We must now consider some of the more common articles 
of food, and study just what needs of the body each sup- 
plies and how each is disposed of in the organism. 

Definition of a food. A food is any substance whose natui'e 
it is when taken into the body to serve for the growth or 
repair of tissue or for the production of energy to be utilized 
in the performance of normal functions. 

Considered from a hygienic point of view, the term food means more 
than the above general definition indicates ; it means a desirable food, 
a nourishing substance which can be recommended as a regular article 
of diet in normal conditions. There are substances which answer to 
the general definition of a food in that they are oxidized in the body 
with the production of energy, and yet cannot be considered as hy- 
gienic foods, since they exert a poisonous action which, offsets what 
benefit the body might get from this oxidation. 

132 



THE HYGIENE OF NUTRITION 133 

Milk. One of the most common and useful articles of food 
is milk. This substance is the sole food of most infants dur- 
ing their first year of life. It must contain, therefore, all the 
substances which are necessary to build up the tissues and to 
produce energy in the body. 

It should not, however, as has been said before, be used as 
the sole food of adults ; for it does not contain the neces- 
sary substances, water, proteids, fats, and carbohydrates, in 
the proper proportions for the bodies of grown men. A 
man has to overwork his organs to get enough milk to pro- 
vide his nourishment. Taken in proper quantity, however, 
there is no food more completely utilized in the body. Its 
proteid elements go to form tissue ; its fats and carbohydrates 
are burned to produce energy. As a rule, it is very easily 
digested.^ 

Cream is the layer of milk which collects upon the top in 
standing. It contains much of the fat of the milJi. 

Butter is made from cream by churning it. It consists 
principally of fat and water. The fat of butter is in a very 
digestible and useful form. 

Cheese is the proteid elements of milk separated. It con- 
tains some fat also. 

EggSj since they are really live animals in an early stage, 

1 Milk in standing about in pails and cans is sure to collect some of the many 
microorganisms which float about. Also the milk from cattle suffei^ing from disease 
may contain the bacteria which cause their disease. One of the diseases which is 
borne in this way is tuberculosis. 

To prevent the taking in of .these bacteria of disease, or these hosts of other bacteria 
which may grow in the body and form substances which may poison the child, the 
milk to be given to children is often sterilized, or Pasteurized ; that is, it is exposed to 
a heat sufficient to kill these bacteria before it is taken. 

The Pasteurization of milk, which is the best method of preparing it for the use 
of children, is accomplished in the following manner : The fresh milk is placed in 
clean bottles which are stoppered with absorbent cotton. The bottles are placed in a 
steamer in which is a thermometer. The temperature of the steamer is raised to 167° 
F., and kept there from twenty minutes to half an hour. The bottles are then removed. 
Milk thus treated will remain steiile for twenty-four hours. The hot air in the 
steamer is, of course, moist. 



134 PHYSIOLOGY AND HYGIENE * 

must contain all the substances which are needed for the tis- 
sues. They are therefore an excellent food. 

Meat. The muscular tissues of animals contain much 
proteid material, and are therefore very useful for building up 
and repairing the body tissues, which, as we have seen, con- 
sist mostly of this substance. The fat of meat is also a 
useful food. 

Fish, like meat, contains much proteid substance. 

Vegetable foods. Vegetables are a very necessary article of 
diet. Some of them contain all the substances which we 
need for both repair and energy, so that man can live in 
good health upon a strictly vegetable diet. This he could 
not do on lean meat, and would find very difficult upon 
milk. The most nutritious vegetable foods are the cereals 
or grains, and some leguminous seeds, as beans and peas. 
These contain much proteid matter for tissue building and 
much carbohydrate for energy formation, also mineral salts. 

Of the grains those in most common use are the wheat from 
which flour for bread is made, and corn. Peas and beans 
are as useful for tissue building as meat, and more nu- 
tritious. 

Many vegetables do not contain much proteid, and there- 
fore are useful for their starch principally. Such are pota- 
toes and rice. The green vegetables, as lettuce, spinach, 
cabbage, are useful for the mineral salts and organic acids 
which they contain, and for their indigestible matter (see 
note, p. 138). Where men are deprived of these or any 
substitute for them they are apt to contract a disease known 
as scurvy. Many vegetables are rich in iron, which is 
necessary for the structure of the blood corpuscles. 

Fruits. Fruits, as a rule, contain much water and small 
amounts of nutritious principles. Apples, for instance, con- 
tain much water, some starch and sugar, and very little pro- 
teid. They are refreshing to the taste, and their large 



THE HYGIENE OP NUTRITION 136 

amount of undigested residue makes tliem useful in keeping 
the bowels open. Bananas are fairly nutritious. 

There are two substances, prepared from the seeds of the 
cocoa fruit, and now much used, which are very useful foods. 
These are cocoa and chocolate. They are nutritious, but with 
many people are difl&cult of digestion. 

Water and salt. Besides these organic food substances 
we have two other important foods. Water is absolutely 
necessary to the organism. A man needs about four pints 
daily. Part of this water he gets with his solid foods, all of 
which contain a considerable amount of water. A certain 
amount, however, he takes separately. Besides the water of 
his food a man should take at least a quart of drinking 
water a daj^ 

Salt is a mineral substance composed of chlorine and 
sodium. We need a good deal of both chlorine and sodium 
in the body as constituents of the tissues. A part of these 
substances we get from other mineral salts contained in our 
meat and vegetables, but most of them we get from this chloride 
of sodium, or common salt. Many foods already contain this 
salt; but, as a rule, we cannot get enough of it from our 
organic food, and have to add it to our dishes in cooking, 
or mix it with them on the table. It is so necessary that 
nature provides for our taking it by causing many foods, as 
meat, not to taste good without it. Animals need this sub- 
stance as well as men, and travel great distances to get it.^ 

Other mineral substances, as lime for the bones, a man gets 
in organic foods, as milk and vegetables, which contain them. 

The use of the different foods in the body. All these sub- 
stances described and all substances which can properly be 
classed as foods supply the body with material for tissue 

1 In the woods or plains one sometimes finds moist, boggy spots or pools of water 
which contain much salt in the water or soil. These are "salt licks." The ground 
about will be found trodden with the marks of animals who come to get the salt. 



136 PHYSIOLOGY AND HYGIENE 

buildiug or for energy. The foods which contain proteids, 
as meats, bread, corn, peas, fish, eggs, milk, are very useful 
for tissue building. Those which are made up chiefly of 
sugar or starch, as potatoes, apples, rice, or of fat, as butter, 
fat meat, cream, are used mostly for energy. As we need 
both tissue and energy, we make our meals of combinations 
of these substances. Where we use up much tissue, as in 
active exercise, we eat more proteid food. Where we need 
more heat energy or body heat, as in cold climates, we eat 
more fat. 

If we eat a sufficient amount of food made up from a com- 
bination of these substances which we have mentioned, meats, 
vegetables, milk, and so forth, we shall get all the material 
which the body needs. 

These foods are all safe. They are suited to the organism 
and they nourish it. They can do no harm to the healthy 
body, unless they are taken in amounts larger than the 
organs can care for, or unless they are out of condition. 
Meats and milk and fruits and vegetables, when taken after 
they have begun to decay or ferment, often cause poison- 
ing. But this is because the process of fermentation which 
brings about the decay in these foods changes their nature. 
From foods they are turned to poisonous substances.^ 

Even though they still may produce energy when taken into 
the body, they are no longer to be considered as foods, since 
their bad effects oifset their useful ones. (See extract, p. 
132, in regard to the definition of a food.) 

Feeding with special foods or compounds. Much has been 
said about special foods being useful for the needs of sepa- 

> The poisonous effects of tainted meats, milk, and other foods are dne to substances 
formed from the fermentation or putrefaction of these foods by microorganisms. 
These are called ptomaines. Similar substances are formed in the body as the result of 
digestive processes, especially when the digestive processes are out of order. Sick 
headache and other illnesses are often due, in all probability, to the absorption of these 
substances thus formed in the body. In normal conditions the body destroys or elimi- 
nates them as fast as they are formed. 



THE HYGIENE OF NUTRITION 137 

rate organs, as foods containing phosphorus for the brain, 
or lime salts for the bones. Now, while it is true that these 
organs need these substances, it is also true that they can 
get all they need of them from the proper mixture of the 
regular foods which we have described. Never in conditions 
of health make a point of taking foods especially rich in 
these substances, as you will often be advised to do. Espe- 
cially is there no need of taking medical preparations and 
tonics to supply these substances. If the diet is a proper 
one, no deficiencies in these regards will exist. If such 
deficiencies are allowed to develop they should be remedied 
by making the diet a proper one. Even in conditions of 
disease a proper diet forms the best medicine in a great 
many cases. 

A proper diet, in the first place, is one sufficient in amount 
to supply the needs of the body for tissue building and pro- 
duction of energy. This means that the day's diet must con- 
tain as much nitrogen, carbon, water, salt, iron, and so forth, 
as the man uses in his day's work. We can find out how 
much a man uses of these substances by measuring the 
amount that he excretes of each of them in his breathing, in 
his urine, sweat, etc. Then if we give him a diet which con- 
tains this amount of these substances, we know that he is 
having a sufficient diet and will be able to work and not fail 
in flesh and strength. Such a diet can be made up in vari- 
ous ways. All of us who are well fed are probably getting 
these proper amounts in our mixed diet of meats, milk, vege- 
tables, bread, and so forth. If we are getting the full sup- 
ply, it makes very little difference of what foods it is made 
up. We can get our nitrogen from meat or eggs or vege- 
tables or cereals as we please, and take the carbon which we 
do not get at the same time in extra amounts of fats or 
other carbohydrate foods, as butter, cream, sugars, and bread. 

Besides supplying the body with a sufficient amount of 



138 PHYSIOLOGY AND HYGIENE 

food and a proper variety, it is best for us to give it also a 
certain extra amount of water and of substances which form 
refuse, as vegetables and fruits. These substances keep 
the system well washed out and clear. A plentiful number 
of vegetables and fruits should therefore be included in the 
diet. These contain much water, and often certain salts and 
acids which are useful in keeping the organs, as the liver and 
kidneys, well cleared out ; and the large amount of indigest- 
ible residue left from them in the intestines helps to keep 
the bowels open.^ 

An example of a healthful diet for a man who works all 
day is given on page 140. Of course some people have 
what are known as idiosyncrasies, and cannot eat certain 
things which are readily digested by most people. People 
who are ill may need a diet made up of easily digested foods, 
but the amount should be about the same as in health. 
But except for such cases such a diet as is given in this 
table is a good one for anybody who works hard with body 
and mind. 

The making of a diet list. Diet tables are made up upon 
what is known as the calorie system. The food is needed, 
as you know, for two purposes, one to build up proteid 
tissue, the other to be burned for the production of en- 
ergy in the body. To provide for tissue building we must 
then see that our diet contains as much proteid or nitrog- 
enous material as the body uses. To provide for energy 
we must see that, the amount of food is so great that if 
burned it mil produce just this energy as heat or something 
else. 

A calorie is a unit of heat. We know just how many 
of these units of heat must be produced daily in the body 

1 As stated on page 104, foods which are easily digested are to be chosen. But a 
certain amount of undigested residue of the proper kind may be useful, as mentioned 
here. 



THE HYGIENE OF NUTRITION 139 

to keep it going, and so we know how many heat units we 
must provide in the food. Now, heat units can be obtained 
from all organic foods, so that it does not matter very much, 
so far as this point is concerned, whether we eat meats or 
bread or vegetables or fat, provided we eat enough. But 
it is easier for our digestive organs to take care of a little 
of each of several foods than much of one kind, so we try 
to get our heat units from proteids and fats and carbo- 
hydrates combined.! Proteids we have to eat in certain 
amount for the nitrogen. The fats and carbohydrates we 
can divide as best suits our taste and digestion, provided, 
only that we take enough of them. 

In the following table the values of the foods included in 
proteid material for tissue building, in calories for energy 
production, and in mineral salts, are given. We know that 
a man at rest needs a food supply of 30 to 34 calories per 
kilogram weight. During hard work he needs a supply of 
from 45 to 60 calories per kilogram. When the food values 
in this table are added up they equal 80 to 130 gm. proteid 
(2J to 4 oz.), 22 gm. salts, and 2,700 to 3,600 calories. As 
the daily needs of a workingman of average weight are from 
80 to 130 gm. proteid, 25 gm. salts, and 2,500 to 3,500 cal- 
ories, this forms an ample diet. It includes also a plentiful 
supply of vegetables, acids, and cellulose substances, which 
serve to keep the excretory functions of the body in good 
action. It includes a fair division of proteids, carbohy- 
drates, and fats. The extra salt which is needed to make 
the 25 gm. is supplied by additions of table salt while the 
food is being prepared and at mealtime. 

A diet of this kind supplies the body with a considerable 
amount of water. The remainder of water needed, about 
one quart, is taken by drinking water during the day. 

1 See note, page 91. 



140 



PHYSIOLOGY AND HYGIENE 



BREAKFAST 



Proteid, gm. 



4-6 



150-200 



Mineral 

SalU, 
gm. 



.001 



5-6 


120-140 


3 


4-7 


150-300 


.5 


.2 


120 


.5 


12 


150-180 


.5 


0.5-1 


50-150 


.1 



200 gm. (about 6 oz.) porridge 
—oatmeal, rye, barley, Indian 
meal, or wheat 

8 gm. sugar on porridge 

100 gm. milk on porridge 

50 to 100 gm. bread, 1 to 3 slices 

15 gm. butter 

2 eggs, or 50 gm. steak or chops 

Fruit— orange, apple, or grapes 



DINNER 

120 gm. consomme or chicken 
broth, or potato, pea, or tomato 
puree with salt 1-5 100-200 1 

100 to 200 gm.beef, chicken,lamb, 

ham, or sweetbread 20-25 200-400 1 

Or 200 gm. bluefish, salmon, hali- 
but, cod, or mackerel 12-20 150-300 

50 gm. potatoes 1.5 60 ,5 

100 gm. spinach, asparagus, or 

squash 1 100-200 .5 

75 gm. peas, beans, macaroni, 

or corn 9-15 300 3 

Custard, or ice cream, or Indian 
pudding, or rice or bread pud- 
ding 6-15 150-250 1 

Cheese and crackers 2-5 300 1 

SUPPER 

Bread and butter 5-7 200 1 

Cocoa, one cup 6 150 1 

Milk, one glass 8 200 3 

Stewed fruit, pears, baked ap- 
ples, peaches with cake, or 

griddle cakes 3-4 200-300 .1 

Approximately, 80-130 gm. 2,650-3,600 21.71 

In addition to liis regnlar food man consumes certain sub- 
stances, as condiments and beverages, which are not taken as 
food to nourish the body, but for the sensations which are 
obtained by taking them. 

1 1 gm. — 15.434 grains troy. 



THE HYGIENE OP NUTRITION 141 

Condiments. Some of these condiments are pepper, vine- 
gar, cloves, nutmeg. They give the food certain flavors 
which excite the appetite and appeal to the sense of taste. 
Frequently, however, their use does harm, as thej^ may set up 
irritation of the digestive organs and excite abnormal secre- 
tion. As already stated, a healthy man needs no stimulation 
for his appetite other than hunger. 

Beverages. The common beverages which men take with 
their food or separately are tea, coffee^ cocoa, or chocolate, and 
alcoholic liquors. 

The alcoholic beverages, beer, wine, whisky, and so forth, 
are taken for the pleasure which they give from their taste 
and from their effect upon the nervous system. These sub- 
stances cannot be recommended as foods. On the contrary, 
every one should be cautioned to avoid them ; for the dan- 
gers which attend and the evils which result from their use 
are serious and out of all proportion to the benefits which 
this use can bestow.^ 

Our ordinary food substances, such as wheat, sugar, 
meat, give us our tissue material and our energy in the 
amount necessary for our nutrition without poisoning or 
danger of poisoning. These substances should therefore be 
chosen as foods, and not alcohol or any other substance 
whose use is fraught with danger. 

If a person desires some other beverage than water with 
his food, he would best use cocoa or chocolate. These sub- 
stances, as we have said (see p. 135), have a just claim 
to be considered good foods ; they furnish at the same time 

1 It matters not that alcohol is oxidized in the body with the liberation of energy. 
So also are several of the organic poisons, as, for instance, muscarine, the active prin- 
ciple of the poisonous mushrooms. Yet no one thinks of classing these substances as 
foods. 

Alcohol has a poisonous action, and since this action is exerted in such a way as to 
make the sum total of its effects harmful whenever enough is taken to prove a practical 
factor in energy production, alcohol should not be classed with the foods. 



142 PHYSIOLOGY AND HYGIENE 

something which ministers both to the taste and to the needs 
of the body. 

Tea and coffee are taken simply for their pleasurable 
effects. Since they do not assist in the nourishment of the 
body it is a question whether they should not be considered 
harmful to it in all cases ; for they exact a certain amount 
of energy from the body in taking them in and disposing of 
them, while they give nothing substantial in return. In 
most cases, however, where they are taken in moderation, 
their harm is slight. With some people they are harmful 
even in moderate amounts. Taken in large amount, they 
are injurious to all people, causing a disturbance of the 
nervous system which is a menace to health and comfort. 
They should never be given to children. 

QUESTIONS 

I. What is the definition of a food? Name one or more single articles 
of food which contain all the materials necessary for the body needs. 
"What is the objection to our living upon one of these foods alone ? Why 
is milk for babies Pasteurized? What are the chief nourishing con- 
stituents of eggs ? Meat? Fish? 

II. How do the vegetable foods compare with the animal for general 
usefulness? Name some of the most nutritious vegetable foods. Why 
should we eat green vegetables and fruits ? What use have these articles 
besides nourishment? How much water do we need daily? 

III. Why do we salt our food? Mention some foods suited to partic- 
ular purposes in the body. To what are the poisonous effects of decayed 
meats or vegetables due? Are such substances properly called foods? 
Do we need to take special foods to get the necessary mineral substances 
for the body? Give the requisites of a proper diet. How do we measure 
the efficiency of a given diet? Are condiments necessary? Name 
some of the common beverages. May any of these be classed as foods? 

IV. Does alcohol provide material for repair of the body tissues? 
Does it increase the capacity of a man for continuous labor? Why 
should it not be classed with the foods? What is the chief and common 
object of the systems of digestion and circulation? Is meat a more 
valuable food than corn? Is anyone food indispensable? Does eating 
fat result in the laying on of fat? 



CHAPTER VII 

ALCOHOL AND ALCOHOLIC LIQUOES 
THEIR USE AND THE RESULTS UPON HEALTH 

THE drinkiug of alcoholic liquors is so common and 
forms so serious an error in the maintenance of health 
that it merits special consideration in a book of hygiene. 

Alcoholic drinks have been used by men for a very long 
time, and although some of their evil results have been seen 
throughout all this time, it is within recent years only that 
man has recognized, through careful investigation of the sub- 
ject, the full extent of their harmfulness. 

Now that their poisonous action is clearly recognized and 
understood, it is necessary that every one should have a 
knowledge of the nature of these substances and their effects 
upon the body, that through this knowledge he may avoid 
them, and thus escape the disease and degradation which 
fall upon so many people who use them, often in ignorance 
of their real nature and effects. 

AlcoJwl, or in chemical terminology ethyl alcohol (C2H5 
OH), is a clear liquid substance looking somewhat like 
water. It has a characteristic odor and a burning taste. 

Source of alcohol. Alcohol is obtained from sugar or sub- 
stances containing sugar by a process known as fermentation 
(Latin fermentmn, " leaven "). 

143 



144 PHYSIOLOGY AND HYGIENE 

Alcoholic fermentation. It was long ago discovered that 
grape juice and apple juice (sweet cider) and many other sub- 
stances containing sugar and water, if allowed to stand in the 
air, become changed in character. From a juice with a 
sweet taste the grape or apple juice becomes a substance 
with a sharp, burning taste. Now, upon comparing the new 
substance with the old, the wine or cider with the grape or 
apple juice, to see what alteration had occurred in it to cause 
this change in its nature, it was found that some of the 
sugar in the old juice had disappeared and been replaced 
principally by two new substances, a liquid, alcohol, and a 
gas, carbon dioxide. It was also found that the alcohol and 
carbon dioxide added together would make up, in a given 
instance, just the amount of sugar which had disappeared, 
except a very slight amount. It was therefore concluded 
that these new substances were formed by the breaking up of 
the sugar. 

Cause of fermentation. Ferments. For a long time the 
cause of this breaking up or decomposition of sugar in 
these liquids was unknown. The amount of starch or sugar 
in apples or grapes kept intact a month does not change, 
nor does any alcohol appear in them. Finally, however, by 
the aid of the microscope it was found that those liquors 
which had undergone alcoholic fermentation, as the cider 
or wine, contained another new substance besides alcohol 
and carbon dioxide. In the liquid were found many minute, 
cell-like bodies which were not present in the juice as it was 
squeezed from the apple. These small bodies were found 
to be live organisms belonging to the vegetable growths 
classed by botanists as SaccJiaromycetes, and known in 
common terminology as the yeast plant. When some of 
these small bodies were put into a liquid containing sugar, 
and the liquor kept fairly warm, it was found that they 
act like a ferment, breaking up the sugar to alcohol and 



ALCOHOL AND ALCOHOLIC LIQUORS 145 

carbon dioxide, that is, bringing about the same action 
which occurred in the cider. It was noted that the yeast 
plants in performing this function grow and multiply with 
great activity.^ From this it was concluded that the small 
amount of sugar which disappeared from the liquor and 
could not be accounted for by the alcohol and carbon dioxide 
produced was consumed by the plant as food.^ 

The process was therefore all explained. These minute 
organisms or plants are floating about in the air or resting 
upon the skin of the ripening grapes or apples. When the 
grape or apple juice is pressed out, some of these yeast plants 
are washed into it, or fall into it from the air. Here they 
begin to feed npon the sugar in the juice, and grow and 
multiply, breaking np this sugar into alcohol and carbon 
dioxide and several other substances, and changing the ap- 
ple or grape jnice into cider or wine (Experiments 1, 2, 3, 
pp. 274, 275). 

The process which thus occurs is called alcoholic or vinous 
fermentation. 

The use of fermented liquors and of the process of vinous 
fermentation by man. As we have said, these products of 
vinous fermentation, the wines and cider, are used exten- 
sively by man as beverages. He takes them partly in con- 
formity to custom and partly for the pleasure which they 
give him, oftentimes in ignorance of the fact that they are 
harmful substances. 

The most common alcoholic beverages produced by 
this process of vinous fermentation are wine, beer, and 
cider. 

Wine, as we have said, is a product formed by the f ermenta- 

1 The yeast plants are little oval-shaped cells so small that they can be seen only by 
the use of a microscope. The ordinaiy yeast which is used by takers in breadmaking 
or by brewers in beer brewing is simply a special preparation of these plants. 

^ Pasteur found that from five to six per cent of the sugar is used for food for the 
yeast plant and to form glycei*in and succinic acid. 



146 PHYSIOLOGY AND HYGIENE 

tion of expressed grape juice. It represents one stage in the 
process of the decomposition of this juice when pressed out 
of the fruit. 

In the manufacture of wine^ man crushes the grapes in a 
vat. Upon the skins of the grapes are many yeast spores.^ 
These get into the juice in the process of crushing and 
mixing, and set up their vinous fermentation. Thus, as the 
juice lies in the vats, alcohol and carbon dioxide are formed 
in it, and it becomes wine. If there is sufficient sugar in the 
juice, the fermentation goes on until the amount of alcohol 
formed is about fourteen per cent. Wlien tlie alcohol in a 
liquor reaches this strength it stops the action of the ferment 
upon the sugar. It poisons the ferment cell so that it can- 
not act, and no more alcohol is formed. The strength of 
alcohol in a fermented liquor may be anywhere from one 
to fourteen per cent. There are wines with a much greater 
per cent of alcohol, but in these the extra alcohol has been 
added. 

Cider is formed by the fermentation of apple juice, as is 
wine from grape juice. Many people are under the impres- 
sion that cider is a harmless beverage, but it is not. It 
contains alcohol like all fermented liquors, and from taking 
this small amount the formation of a permanent craving 
and an alcohol habit has often been developed. 

Beer is manufactured by applying vinous fermentation to 
the decomposition of barley. In brewing beer, the barley, 
which contains starch, is kept in a warm place and moist 
until it sprouts. In the process of sprouting, most of the 
starch is turned to sugar. This step is necessary, as the 
yeast ferment will not act upon starch. After the sugar is 



1 The ferments found most generally upon the surfaces of grapes are Saccharotny- 
ces (sugar fungus) elli/psoideus (ellipse form). Saccharoinyces apicxdati ^from apic, 
"point'"), also found on grapes, is common on all garden fruits. Saccharomyces cere- 
visice (from cerevisia, " beer ") is the ferment of beer yeast. 



ALCOHOL AND ALCOPIOLIC LIQUORS 147 

formed the grain is heated until it is killed, to stop its using 
up the sugar as a food for the young plant. The dead grains 
are then crushed, and the sugar is dissolved out by steeping in 
water. To this mixture of sugar and water, called beer wort, 
the brew^er adds a substance called yeast, which is a mixture 
containing the yeast spores {SaccJiaromyces cerevisice), and 
which causes alcoholic fermentation.^ The liquid then begins 
to ferment, the sugar is decomposed, and alcohol and carbon 
dioxide are formed. The alcohol collects in the liquor. Tlie 
carbon dioxide, a gas, conies up through the liquor in bub- 
bles, and passes off into the air. If the beer is bottled before 
the sugar is all decomposed, the gas is contained in tlie 
liquor, and begins to escape when we open the bottle, thus 
causing the fizz and foam of the beer. 

The making of bread involves the application of the process of al- 
coholic fermentation, which here man has turned to a useful purpose. 
To the mixture of flour and water, the dough, some yeast is added. This 
ferments the sugar in the dough, forming alcohol and carbon dioxide. 
The gas goes through the dough, raising it. When the bread is risen it 
is baked. This drives off the alcohol and expands the gas, which fills 
the bread with small bubbles or holes, and stops the action of the yeast. 
There is therefore no alcohol in bread that is properly baked. 

The product of fermentation contained in these fermented 
liquors to which all the harmful effects of the liquors are 
due is the alcohol. This alcohol can be separated from the 
liquors by a process known as distillation. This process is 
employed in the manufacture of the beverages called hard 
liquors, such as whisky and brand}^ 

Distillation. In the liquor the alcohol is mixed with many 
other substances, as water and sugar, which are less volatile 
than alcohol. That is, if the liquor is heated, alcohol is 

1 Pure yeast ferments siigar only. Mixtures of yeast often contain bacteria, which 
have a diastatic action upon starch and turn it to sugar, so tliat tlie yeast can act upon 
It. In breadmaking, some of the starch is changed m this manner, and the sugar 
formed is fermented by tlie yeast. 
HEWES, P. & H.— jO 



148 PHYSIOLOGY AND HYGIENE 

converted to vapor at a much lower lieat than is necessary 
to convert the water to steam. Consequently the alcohol 
will turn to vapor and pass off before much of the water 
has become hot enough to form steam. Thus, by heating 
we can separate the alcohol from the water and more solid 
substances. Now, if this alcohol vapor is allowed to collect 
in a cold vessel, it wiU condense, and we shall have the 
liquid alcohol. This process of separating alcohol is called 
distillation. The liquor is heated in a closed vessel with a 
pipe running from it which bends downward and empties 
into another vessel. The pipe, or worm, is kept cool by a 
current of cold water. The vapor of the alcohol rises until 
it is past the bend, then is condensed by the cold, and falls 
in drops upon the sides of the pipe, and runs into the receiv- 
ing vessel. 

Distilled liquors. The distilled liquors which are manu- 
factured by this process, the whisky, brandy, rum, or gin, 
contain much more alcohol than the simple fermented licpiors 
from which they are distilled. In the process of their dis- 
tillation some water and also some extracts pass over into 
the distillate. These extracts give the peculiar flavor to the 
different liquors. 

Because these so-called hard liquors contain more alcohol 
than the fermented liquors, they are more harmful ; but it is 
only a question of degree in regard to all alcoholic liquors, 
beer or cider, whisky or rum. The alcohol contained in any 
of these liquors is, when introduced into the body, capable 
of poisoning it. Those who have once seen men under the 
effect of this substance need no further evidence of its poison- 
ous power. Its poisonous effects, however, are not confined 
to these cases where they are so marked as to be plain to 
every observer, cases where men lose their reason, their power 
of coordination and locomotion. A careful study of the 
effects of alcohol in the body reveals, as we shall see, that its 



ALCOHOL AND ALCOHOLIC LIQUORS 149 

action is often insidious, often for a long time giving no sign, 
even to the drinker himself, of the poisonous effect upon his 
health and strength that it is exerting. ^ 

THE ACTION OF ALCOHOL WITHIN THE BODY UPON 
THE VITAL FUNCTIONS 

When any alcoholic liquor is introduced into the body, a 
portion of the alcohol is oxidized there. In being oxidized, 
alcohol is broken up into water and carbon dioxide, and the 
energy contained in the compound is liberated. Some of the 
alcohol, however, passes through the body unchanged, and 
is eliminated in the urine and the breath. 

The action of alcohol upon the constitution and functions 
of the body is a complex one. To some extent, as stated, it 
liberates energy for the performance of the vital functions, 
that is for heat or work; but it also acts upon the nervous 
system, or upon cellular activity throughout the body, in a 
manner detrimental to these functions. 

I Dr. Adolf Fiek, Professor of Physiology in Wiirzburg, Grermany, says : ' ' From an 
exhaitstive definition we shall have to class every substance as a poison vrhich, on 
becoming mixed with the blood, causes a disturbance in the function of any organ. 
That alcohol is such a poison cannot be doubted. . . . Very appropriately has the 
English language named the disturbance caused by alcoholic beverages intoxication, 
which, by derivation, means poisoning." 

Ethyl alcohol, even when diluted as in wine, beer, and cider, is a poison which 
changes pathologically the tissues of the body and leads to fatty degeneration. Of 
course 1 am not speaking here of the smallest doses. However, the latter (for ex- 
ample, half a liter of beer or a glass of wine) are also poisonous, because they injure 
the brain by producing paralysis and derangement of function ; that is clearly demon- 
strated by the experiments of Kraepelin, Smith, Fiirer, Aschaffenburg, etc. The 
same have never been controverted. The most moderate drinking of alcohol is quite 
useless for the individual, but by means of example and fashion produces an incalcu- 
lable social injury and misery to the masses, since all cannot remain moderate, and 
the entirely moderate remains at last the exception.— Dr. August Forel, Professor 
of Psycliiatry in tlie University of Zurich. 

All the alcohols are poisons. — Dujardin-Beaumetz and Audige. 

Is alcohol a poison? I reply. Yes. It answers to the description of a poison. It 
possesses an inherent deleterious property which, when introduced into the system, 
is capable of destroying life, and it has its place with arsenic, belladonna, prussic acid, 
opium, etc. — Dr. Willard Parker, late Professor of Surgery in the College of Physicians 
and Surgeons, New York ; Consulting Physician to Bellevue, Mount Sinai, Roosevelt, 
and the New York hospitals. 



150 PHYSIOLOGY AND HYGIENE 

It is oiir concern in the study of hygiene to determiDe, if 
we can, just what the sum total of its effects is, when taken 
in the amounts and manner in which it is ordinarily used 
by men as a beverage. In other words, we wish to know 
whether the balance of its various separate effects upon the 
vital functions of the body is helpful or harmful. 

Effect upon vital functions. We know that if strong alcohol 
is applied to the cells of a growing plant, or to the body cells 
uncovered in a w^ound, these cells are deprived of their vitality 
and finally die. Doubtless this would be the effect of alcohol 
upon living cells anywdiere in the body, if it reached them 
directly and in full strength ; but w^hen taken in beverages it 
does not reach the body tissues in fuU strength, but much 
diluted. What we want to determine, therefore, is whether 
the effect of alcohol in this diluted form in which it cir- 
culates in the bodj^ of men w^ho use it as a beverage is also a 
deleterious one upon the vitality and function of the cells 
therein. 

The way to determine this question is to study the effects 
of alcohol upon the persons Avho drink it. In this investi- 
gation Ave at once- find evidences of this deleterious action. 
These evidences are, of course, most marked in the cases of 
persons who di-ink large quantities of liquor. Here we find 
marked disturbance of the functions of the brain, the diges- 
tive organs, the heart, loss of vitality of the tissues dur- 
ing life, and degeneration of these tissues in the exami- 
nation after death. But the evidence of deleterious action 
is not confined to these cases of hard drinkers. It is found 
also in the cases of men w^ho drink alcohol in such small 
quantities, for instance, as are ingested in the practice of 
what is commonly called '' drinking in moderation." ^ 

1 All alcohol, and all things of an alcoholic nature, injure the nerve tissues pro tem- 
pore, if not altogether, and are certainly deleterious to the health. I think there is a 
gi'eat deal of injury being done by the use of alcohol in what is supposed by the con- 
sumer to be a most moderate quantity, to persons who are not m the least intemperate, 



ALCOHOL AND ALCOHOLIC LIQUORS 151 

This evidence, which tends to show that the drinking of 
alcohol even in moderation is injnrions, is best obtained in 
the investigation of the effect of this drinking in modera- 
tion npon two of the vital functions of the body, that of 
muscular work and that of maintaining the body heat. 

The end and aim of all the body processes is to work. To 
accomplish this end the body must keep warm. The more 
perfectly the body can accomplish these conditions, the 
more able is the possessor of that body to make his way 
in the world. Now, alcohol, taken even in what is con- 
sidered moderation, lessens the power of the body to work 
and to maintain its heat supply. 

This conclusion is based upon experiments conducted 
upon large numbers of men during long periods of time. 
The results in regard to the effect of alcohol upon the 
capacity for work were obtained from investigations in the 
large armies of the world during active campaigns (see 
p. 80). Those in regard to the effect upon the maintenance 
of the body heat were obtained in part from scientific in- 
vestigations carried on by physiologists in all parts of the 
world, in part from investigations conducted among the 
members of companies of arctic explorers. 

In the light of our present knowledge, then, it is evident 
that alcohol as a beverage lessens the usefulness of the body. 

A certain amount of alcohol is undoubtedly oxidized, and 
can be utilized for the production of energy for the body ; but 
in the ordinary conditions of labor and exposure to which 
man is subjected, the benefit which the body can receive 
from it, in cases where enough alcohol to prove a practical 
factor in energy production is taken, is more than offset by 

and to people supposed to be fairly well. It leads to degeneration of the tissues ; it 
damages the health ; it injures the intellect. Short of drunkenness, that is, in those 
effects of it which stop short of dininkenness, I shoxxld say from my experience that 
alcohol is the most destructive agent we are aware of in this country.— Sir William 
Gull, M.D., r.R.S., Consulting Physician to Guy's Hospital, London. 



152 PHYSIOLOGY AND HYGIENE 

the deleterious effect of the alcohol. The sum total of the 
effect is therefore harmful. 

In addition to evidence obtained by physiological investi- 
gations, we have the evidence of statistics in regard to the 
health and mortality of people who use alcohol, and of those 
who do not. These have been collected in England by the 
life-insurance companies. They indicate that the life of 
the abstainer is, on the average, longer than that of the 
drinker. 

Also, it has been found that the hospitals get their in- 
mates to a much greater extent from the drinkers than from 
the abstainers. The drinker is less able to resist infection, 
and the physicians of these hospitals all acknowledge that, 
once infected with a serious disease, the chances of the 
alcohol drinker are much less than those of the abstainer. 

In regard to sunstroke, for instance, a condition which is 
so common in our great cities during the summer mcmths, 
Osier, in his " Practice of Medicine," makes the following 
statement: "In the larger cities of this country the cases 
[of sunstroke] are almost exclusively confined to workmen 
who are much exposed, and at the same time have been 
drinking beer and whisky." ^ 

In addition to what directly harmful effects alcohol may 
have upon the health through its action upon the tissues or 
body functions, its use has another possible effect, which 
has to be taken into account in any consideration of tliis use 
from a hygienic point of view. This effect is the formation 
of what is known as the alcohol hahif. A description of this 
deplorable condition is given in the sections on alcohol and 
the alcohol habit in Chapter XI. It is sufficient merely to 
mention it here as one of the dangers attending the use of 
alcohol. 

1 Tlie late Surgeon Parke, medical officer of the Emin Pasha relief expedition, said : 
"Drink is certainly Ihe most powerful predisposing cause of the development of the 
symptoms of sunstroke. " ' 



ALCOHOL AND ALCOHOLIC LIQUORS 153 

The indulgence in any practice involving risk from the 
point of view of health or welfare is justifiable only in cases 
where the benefit to be derived from the practice is propor- 
tionate to the risk involved, and where the same))enefit cannot 
be obtained in some manner involving less or no risk. The 
danger of the use of alcoholic drinks, and the harm which 
may follow this use, are, in a general average, out of all pro- 
portion to the possible benefit which is or can be derived from 
it. This use is therefore unjustifiable, and should be con- 
demned in all manuals of hygiene. 



QUESTIONS 

I. What is the source of alcohol? Describe the fermentation of 
alcohol. What is the cause of this process? What is beer? Wine? 
Cider? 

II, What are distilled liquors? Describe breadmaking. What are 
some of the harmful effects of the drinking of alcoholic liquors upon the 
vital functions of the body? Give the principal reasons for avoiding 
the use of alcoholic beverages. 



CHAPTER VIII 

CIRCULATION AND THE CIRCULATORY SYSTEM 

WE have already spoken of the circulatiou of the blood 
and lymph in describing its connection with the dis- 
tribution of the nourishment to the tissues. Besides this use, 
the circulation has two other functions. One is the bearing 
of the free oxygen to the tissues, the other the carrying away 
of the waste products of tissue combustion to the excretory 
organs. 

We must now stud}- the organs by which this function of 
circulation is accomplished. These are the heart. Avliich 
pumps the blood about tlie body ; the blood vessels, which 
carr}' this stream of blood ; and the lymphatics, which carry 
the lymph. 

I. THE HEART 

The heart is a hoUow muscular organ, whose function it is 
to pump the blood about the body. It lies in the thorax, 
just above the diaphragm, behind the sternum and the rib 
cartilages on the left side. It is attached at its base to the 
great vessels. 

The pericardium ( Greek j;m, ''around," and ^Y/r(f?rt, "heart"). 
Inclosing the heart is a sac called the pericardium. This 
sac lines the heart externally, and then leaving it at the 
base, folds upon itself and completely surrounds it again. 

154 



CIRCULATION AND THE CIRCULATORY SYSTEM 155 



The pericardium is a connective tissue structure lined upon 
its free surface by a thin membrane of epithelial cells known 
as a serous memhrane (a membrane made up of cells which 
discharge a serumlike 
or wheylike substance). 
These free surfaces of 
the two parts of tlie peri- 
cardium, the part lining 
the heart and the part 
forming the sac, move 
freely upon each other 
with the movements of 
the heart. The cavity 
between them contains 
a little fluid secreted by 
the cells of the serous 
membrane. 

The heart is conical in 
shape, the broad end, or 
base,uppermost, the cone 
end, or apex, below. The 
apex lies opposite the 
point of the chest wall 
at which we can feel the 
heart beat most strongly, 
between the fifth and sixth ribs to the left of the sternum. 
At the base of the heart the large arteries run out. Here at 
the base on each side is a flat, soft, earlike structure connected 
with the firmer part below. These flabby structures are the 
appendages of the auricles (Latin auris, ''ear") of the heart. 
The firmer parts below inclose the ventricles (Latin venter, 
''belly"). 

The heart consists of four chambers — two auricles, right 
and left, and two ventricles, right and left. At the base, 




Heart aud lungs in chest. 

a, arteiies and veins to head (right) ; ft, arteries, 
veins, and nerves to ai-m (left) ; h, heart ; I, Inng 
(drawn hack) ; p, pericardium. 



156 



PHYSIOLOGY AND HYGIENE 



posteriorly and to the left, lies the left auricle. In the com- 
paratively thin walls of this cavity are four small openings, 

the apertures of the pulmonary 
veins, which bring- the blood from 
the lungs. In the lower wall of 
the auricle is a large opening 
to the left ventricle. 

The left rent ride lies in the 
lower part of the heart, to the 
front and left. The walls of this 
cavity are very thick and firm. 
Upon its upper wall is the open- 
ing from the left auricle. This 
opening is covered by a valve 
made up of two flaps, the bicus- 
pid or mifraJ (Greek niifra, "head- 
•Iress ") valve. The bases of these 
valve flaps are fixed about the 
auric ulo-ventricular opening. 
Their edges are held by connec- 
tive tissue cords connecting with 
the ventricular walls, the cJwrdce 
tendinece (Greek chorda, '^cord," 
and teuein, "to stretch")- These 
cords keep the valve from pressing back into the auricle 
under the pressure of the blood in the ventricle. The valve 
allows the free flow of the blood from auricle to ventricle, 
but stops any back flow from the ventricle when the ven- 
tricle contracts. In the front part of the ventricle, in front 
of the auricular opening, is the opening to the aorta. This 
opening is covered by a valve consisting of three flaps, each 
shaped like a half moon, the semilunar (Latin semi, "half," 
and hiua, " moon ") valve. This valve aHows the blood to flow 
from the ventricle to the aorta, but not back from the aorta. 




Heart, with aorta. 



CIRCULATION AND THE CIRCULATORY SYSTEM 157 



At the base of the heart, to the right, separated from the 
left auricle b}" a partition or septum, is the right auricle. 
In the right wall of this auricle is the opening of the two 
large veins which col- 
lect the blood return- 
ing from the tissues 
to the heart, the stqje- 
rior and inferior vena 
cava ("hollow"). 

In the lower anteri- 
or part of the auricle 
is the opening of the 
right ventricle. This 
is covered by a three- 
flap valve, the tricus- 
pid (Latin tri^ " three," 
and cuspis, " spear 
point") valve. It pre- 
vents regurgitation 
(Latin re, *' again," 
and gurgitare, "to en- 
gulf") of the blood 
from ventricle to 
auricle. 

The right ventricle 
lies in the lower part 
of the heart, to the 

right. It is separated from the left ventricle by a septum. 
The walls of this ventricle are thicker and firmer than those 
of the auricle, but less thick than those of the left ven- 
tricle. At the top of the ventricle, toward the front, is the 
opening to the pulmonary artery. This opening is covered 
by a set of seniilimar valves similar to those of the aortic 
aperture. 




Interior of heart, showing right auricle 
and ventricle and valves. 

rt, auricle; c, semilunar valve; i, inferior vena 
cava; p, pulmonary artery: s, superior vena cava; 
t, tricuspid valve ; v, ventricle. 



158 



PHYSIOLOGY AND HYGIENE 




Heart valves. 



Structure of the heart. The heart is composed of muscular 
tissue of a special kind, described iu the chapter upon the 
muscles. This muscular wall is lined without by the cardiac 
layer of the pericardium, within by a membrane known as 

the endocardium (G-reek en- 
don, " within," and I'ardia, 
"heart"). 

This membrane has a 
single layer of epithelial 
cells upon its inner sur- 
face, and is continuous 
with the inner lining of 
the arteries and veins, the 
endothelium. 

The valves are formed 
of connective tissue lined 
with the endocardium. 
The heart is nourished by arteries from the aorta, known 
as the coronary (Latin corona, " crown ") arteries. Its action 
is controlled by a special plexus of nerve ganglia (Greek 
f/afj(/lion, "ganglion "—"a knot"), located in its substance 
and connected with the central nervous system. 

The action of the heart. The action of the heart is brought 
about by the contraction of its muscular walls. When the 
muscle fibers contract they l)ecome shorter and thicker, and 
thus diminish the size of the cavities which they inclose. 
By the same muscular action the walls of the cavities are 
drawn toward each other as well as contracted. Thus, when 
a contraction of the walls of a cavity occurs, the cavity is 
neaj'ly obliterated, and the blood forced out of it, just as 
squeezing a rubber ball with a hole in it obliterates its 
ca\dty, and forces any fluid in it, as water, out. 

The contraction of the heart walls is called a systole (Greek 
sustole, "a contraction"). When the walls have thus con- 



CIRCULATION AND THE CIRCULATORY SYSTEM 159 

tracted they relax again, opening the cavities and allowing 
an inflow of blood from the veins. This relaxation is 
called diastole (Greek, "dilatation"). 

Now, in the action of the heart, the two anricles contract 
together, and this is followed at once by a contraction of the 
ventricles. Then there is a panse during which the heart 
relaxes and the cavities all open again, then a contraction 
again, and so on. These rhythmic contractions of tlie 
heart make what is known as the teat of the heart. This 
beat can be felt, especially after exertion, as a thumping of 
the heart against the chest wall (Experiment 3, p. 34). 

The sounds of the heart, which you can hear by laying 
your head, ear down, upon the pillow, are two— a long one, 
like liib, followed by a short one, dn}). The first sound is 
due to the contraction of the heart, the second to the clo- 
sure of the valves. 

The passage of the blood through the heart. At the begin- 
ning of the heart beat the auricles contract. The right 
auricle, which has filled with blood from the large veins 
of the body, the vence cavce, contracts and forces the blood 
into the right ventricle. This contraction of the auricle 
closes the flaccid openings of the veins in its walls, so that 
none of the blood is forced back into them, but all onward. 

As the auricular contraction ends, the right ventricle, which 
thus has been filled with blood, takes up the contraction, 
forcing the blood into the pulmonary artery, and thus into 
the lungs. The whole contraction of both auricle and ven- 
tricle passes over the heart like a wave, starting at the 
auricular end and ending at the ventricular. 

In the contraction of the ventricle, the flaps of the tri- 
cuspid valve close the auricular orifice and prevent a reflex 
of the blood from the ventricle in this direction, so that it 
can go on only into the pulmonary artery. 

While the ventricle is contracting, the aiuicle is relaxing, 



160 



PHYSIOLOGY AND HYGIENE 



and as it does so a new supph^ of blood flows into it from 
the veins. This blood in turn is forced into the ventricle as 
this relaxes, and so on through beat after beat. In the re- 
laxation of the ventricle, the semilunar valve of the pulmo- 
nary artery is closed over the ori- 
fice by the back pressure of the 
blood in the overfilled artery, and 
thus the back flow of blood into 
the ventricle is prevented. 

The blood is forced along the 
pulmonary artery to the capil- 
laries of the lungs by the force 
of the beat of the ventricles, and 
from these capillaries into the 
pulmonary veins, and so back to 
the left auricle of the heart. 

At the same time that the right 
auricle is contracting upon the 
blood of the general circulation 
which it has received, the left 
auricle is contracting upon the 
blood which it has received, as 
above described, from the lungs 
by the pulmonary veins. This 
blood it forces into the left ven- 
tricle. The left ventricle con- 
tracts at the same time with the 
riglit, and presses the blood x)ast 
the semihmar valves into the aorta, and thus into the gen- 
eral circulation. The pressure of the blood upon the mitral 
valve closes it, and prevents regurgitation of the blood into 
the auricle. When the ventricle dilates again, the semilunar 
valve of the aorta prevents reflux of the blood to the ventricle. 
The impulse of the left ventricle forces the blood aloug 




Diagram of the circulatory 
system. 

J7, heart; L, kings; i, intestine; 
F, liver; K, kidneys; 6, aorta; b'. &x- 
teiles to head and Tipper extremities ; 
h". arteries to tinink and lower ex- 
tremities; c, v-enae cavjB; c', veins 
from upper extremities; c", veins 
from lower extremities; d. pulmo- 
nary ai'tery ; e, pulmonary veins ; 
/. portal circulation ; g, renal circu- 
lation. 



CIRCULATION AND THE CIRCULATORY SYSTEM 161 

the aorta to the arteries and capillaries throughout the body. 
From the capillaries it is returned by the veins to the right 
auricle, thence as described to the right ventricle, lungs, and 
left auricle, and into the ventricle again. Thus by the im- 
pulse of the heart the blood is kept flowing in a big circular 
course over the body. 

Work of the heart. The heart beats seventy times a min- 
ute. At each beat each ventricle forces six ounces of blood 
along against the back pressure of the blood in the vessels. 
When all this work is calculated, it will be found that the 
heart in one day does work equal to raising a ton. of coal 
nearly two hundred feet. 

II. THE BLOOD VESSELS 

The vessels which carry the blood in its course around the 
body are divided into three classes. 

The arteries are the vessels which carry the blood from 
the heart to the capillaries and tissues. 

The capillaries are very fine vessels which carry the blood 
from the arteries through the interstices of the tissues. 

The veins carry the blood from the capillaries and tissues 
back to the heart. 

(See plans of arterial and venous systems, pp. 164, 165.) 

Structure of the vessels. The whole circulatory system is 
one continuous tube. The endocardium, or inner lining 
membrane of the heart, is continued throughout the arteries, 
capillaries, and veins. In the vessels it is called the endo- 
thelium. This endothelium, like the endocardium, consists 
of a single layer of epithelial cells. The walls of the capil- 
laries, the smallest vessels, consist simply of this endothelial 
membrane. In the small arteries a layer of muscular and 
elastic tissue is placed outside this endothelium, and a con- 
nective tissue layer outside of this. In the large arteries 




162 PHYSIOLOGY AND HYGIENE 

the muscular layer is very thick and contains much elastic 
tissue. 

The arterial walls consist, then, of three layers : first, an en- 
dothelial ; second, a muscular and elastic ; third, a connective 

tissue layer. The elastic 
tissue nuikes the arterial 
wall very firm and elastic. 
When an artery is cut it 
does not collapse, owing to 
the firm tissue in the walls. 
,,, ,, . , The walls of the veins 

v\ all ul artery. 

consist of three similar 
layers. They contain, however, much less muscular and 
elastic tissue, and thus collapse when cut. 

Plans of the arterial and venous systems. The arterial 
system begins with the aorta (1).^ This vessel leaves the 
left ventricle at the base of the heart and runs upward, 
forming an arch in the upper part of the chest. 

From the convexity of this arch arise three large arteries— 
the innominate (2) (Latin in-nomen, ''unnamed"), which 
divides into two trunks, the right carotid (5) (Greek Jcciros, 
" stupor"), which supplies the neck and head, and the 
rigJit suhclavian (6) ("under the clavicle"), which supplies 
the shoulder, arm, and hand on the right side ; the Jeff 
carotid (3), which supplies the left side of the neck and head ; 
the left subclavian (-4), which supplies the left upper limb. 
Each subclavian runs across the armpit as the axillari) 
arterj^, then down the arm to the elbow as the hracliial 
(G-reek hrachion, " arm "), dividing there to the radial and 
ulnar arteries to the forearm and hand. From the arch 
the aorta runs downward along the front of the spine as 
the thoracic aorta (7), giving off branches to the walls of the 
thorax. Piercing the diapliragm, this artery becomes the 

1 Figures refer to plate of the circulatory system, page 164. 



CIRCULATION AND THE CIRCULATORY SYSTEM 163 

abdominal {Lutm ahdere, "to conceal'') aorta (8), which gives 
off the coeliac (Greek Jioilia, "belly'') axis (9) to the stomach, 
liver, 'dud spleen, the mesenteric arteries to the intestines, 
the renal arteries (10), and several smaller branches. 

At the level of the fonrth Inmbar vertebra the abdominal 
aorta divides to take two common iliac (Latin ilia, *• flanks '') 
arteries (11), a right and left. Each iliac artery supplies its 
side of the pelvis and continues into the leg, being called 
the femoral artery in the thigh and the popliteal (Latin 
poples, "the ham") at the knee. This artery divides to the 
peroneal (Latin perone. " fibnla") and the posterior tibial, 
w^hich supply the leg and foot. 

The veins begin as small twigs collecting the blood from 
the capillaries. These small branches coalesce to larger 
trunks until finally the venous blood is collected into the 
two large veins, the superior vena cava (IV) and inferior vena 
cava (V), w^hich pour it into the heart. 

The blood from the head and neck is brought by the jugular 
(Latin jiigulum, " throat ") veins (c) to the chest. The blood 
of the hand, arm, and shoulder is brought to the chest 
by the subclavian vein {b). In the chest the jugular and sub- 
clavian veins of each side unite to form the innominate [a). 
The tw^o innomi nates thus formed unite to form the superior 
vena cava (IV), w^hich runs to the heart. The intercostal 
spaces are drained by the azygos (Greek a, '' without," and 
zugos, " yoke") vein, which enters the superior vena cava. 

The veins of the low^er limbs unite to form the inferior 
vena cava. This receives the veins from the pelvis, the kid- 
neys {g) (renal veins), and the Kver, and enters the heart. 

The blood from the alimentary tract, the stomach and 
intestines, and that from the spleen is collected by the 
portal vein. This carries it to the liver, where the vein 
divides into fine capillaries like an artery. The blood 
from the capillaries, purified by the liver 'cells, is again 



,.-=^ 



rfi/s 



C^ A / 



'^to: 




Tlie cireiilatoiy system, 
right aiu-ide ; i>Meft auricle; C, right ventricle ; X>, lt?ft ventricle ; K, kidneys 



lU 



CIRCULATION AND THE CIRCULATORY SYSTEM 165 



collected by the hepatic vein, which enters the inferior vena 

cava {li). 

The pulmonary circulation. In addition to this general 

system of circulation, there is a subsidiary system, the 
pulmonanj (Latin j;y(Z- 
mOy ''lung") system. 
The venous blood 
returned to the heart 
has to be sent to the 
lungs for purification 
before it is again sent 
through the body. 

The blood is taken 
from the right ven- 
tricle by the pulmo- 
nary artery (II), which 
divides in the lungs, 
to capillaries. From 
these capillaries the 
blood is collected and 
borne back to the 
heart by the pulmo- 
nary veins (III). 

III. THE LYMPHATICS 

The lymph, like 

the blood, circulates 

in vessels. These are 

called hjmjyJiatics. In 

the tissues, the lymph 
is free in the spaces among the cells. These spaces are 
drained by a network of delicate vessels. These lymphatic 
vessels, like the veins, unite to form larger ones, until finally 





Veins in arm and 
hand. 



Arteries in arm and 
hand. 



166 



PHYSIOLOGY AND HYG^IENE 



1, 




the lymph is collected into a left and right vessel of large 
size, which empties it into the veins. The large trunk of 
the left side is called the thoracic 
dvct. This receives the lymph from 
mMi i WL-^^0''^'^^ both lower limbs, the abdominal 
fflff S^^^ ^^ viscera, and the left thorax, arm, 
f if, ]\rZ^^ and side of the head. 

In addition to the lymph from the 
tissues, the lymphatics carry to the 
veins the chyle, which is absorbed 
from the intestines. This chyle is 
the part of the food which absorbs 
into the lacteals, one of which runs 
in the center of each villus. These 
lacteals run into larger trunks, which 
finally enter the thoracic duct. 

In structure th.e walls of the lym- 
phatic vessels are composed of an 
endothelium, a muscular layer, and a 
connective tissue layer. 

The flow of the lymph in these 
vessels is due to the pressure in the 
tissues, where, as described, there is 
a constant overflow of lymph. 

Lymphatic nodes. In the course of 
the lymphatics are numerous struc- 
tures known as hjmpli nodes or lymph 
glands. These nodes consist of clus- 
ters of cells bound together by con- 
nective tissue. They are a part of the 
lymphatic tubes, filled with cells, 
through which the lymph filters in 
its coiu'se. In this passage through the node th-. lymph is 
purified, certain of its contents being taken out or worked 



'd 



Lymphatics of arm. 
a lymphatic nodes of axilla. 



CIRCULATION AND THE CIRCULATORY SYSTEM 167 

over by the gland cells. The lymph also takes up cells 
from these nodes, which are thus poured into the blood and 
become the white corpuscles there, since these corpuscles, 
many of them at least, are simply free lymph cells. These 
nodes are called glands, in many books, but are not glandular 
structures. 

The spleen. There is one large and important structure 
in the body classed with the lymph nodes. This is the 
spleen. It is often called a ductless gland. 

The spleen is a dark purplish-red organ about five inches 
in length, situated on the left side of the abdomen, just in- 
side the lower ribs. 

In structure the spleen is a big lymph node. It consists 
of a connective tissue framework like that of a sponge. 
In the meshes of this spongy frame is a soft pulp, the 
spleen pulp. This pulp consists of red blood corpuscles, 
of white blood corpuscles, and other cells. Throughout 
the spleen are small white nodules consisting of groups 
of leucocytes. Here in the spleen these white corpuscles 
multiply, and then are poured into the blood as white 
blood corpuscles, just as they are poured into the lymphatics 
from the lymph nodes. The red corpuscles which have 
been used in the blood are probably collected and broken 
up here. 

The spleen is supplied by an artery, and its vein emp- 
ties into the portal system. The blood flows freely through 
the pulp, permeating it everywhere. 

IV. THE METHOD OF THE CIRCULATION THROUGH THE 
VESSELS 

In the circulation the blood is forced through the series 
of elastic tubes, the arteries, into the smaller capillaries. 
The passage of the blood through these vessels, particularly 

HEWES, p. & H.— 11 



168 PHYSIOLOGY AND HYGIENE 

the great number of minute capillaries, gives rise to much 
friction. This friction is the resistance which the heart has 
to overcome by its impulse. The vessels are always full of 
blood. The aorta and arteries are kept more than full — 
distended. 

This pressure on the walls by the excess of blood in the 
vessels is called the Uood pressure. The distended elastic 
walls are constantly tending to contract to their regular 
size, and in so doing they are exerting a constant pressure 
upon the blood within the vessels, forcing it onward into 
the capillaries and veins. 

The distention is kept constant by the supply of blood 
which the heart is regularly pumping in. Thus during 
life there is always a distention of the vessels, with a con- 
stant flow along them in the direction of the capillaries and 
veins (Experiments 3, 4, p. 177). 

When the heart pumps, the distention is increased mo- 
mentarily, and there is a spurt of blood into the small ves- 
sels. Thus, when an artery is cut, the blood will flow in a 
continual stream, but with this there will be at regular 
intervals an extra flow or spurt. 

When the blood gets to the veins much of the force has 
been used up in friction, so that the blood flows under less 
pressure here. 

The whole flow of the blood is due to the pumping of 
the heart. This flow is regulated and guided, however, by 
the muscular, elastic walls of the vessels. 

The pulse. When the heart pumps the blood it causes a 
distention of the walls of all the arteries. Where a large 
artery runs near the surface of the body, as the radial artery 
in the wrist, we may feel this wave of distention with the 
finger. This we call the pulse. This pulse does not extend 
to the veins. Here the blood flows steadily, but with very 
little force, as a large amount of force is used up in the fric- 




CIRCULATION AND THE CIRCULATORY SYSTEM 169 

tion of the passage through the capillaries. What remains, 
however, serves to take the blood back to the heart. 

The valves of the veins. On account of this low pressure, 
the veins, especially those of the limbs, are provided with 
valves which open to the blood flowing toward the heart, but 
close against any back flow, and thus tend to 
keep the blood flowing in one direction under all 
conditions. The position of these valves in the 
superficial veins of the front forearm may be 
seen by exercising the arm, and then compress- 
ing it at the wrist. The valves appear as little 
swellings in the course of the blue veins. 

The vasomotor (Latin rasa, " vessel," and inoveo, 
'^ I move ") regulation of the circulation. We 
have said that the blood vessels of the body are 
always full. This universal fullness is main- 
tained by an automatic (Greek auto, " self," and matos, 
"spontaneous," "self-acting") regulation of the caliber of 
the vessels in different parts of the body, in accordance with 
the amount of blood in them. 

There is not enough blood in the body to keep all the 
vessels distended if each is relaxed to its full extent. But 
they are never all thus relaxed. Each artery adapts its size 
to the amount of blood in it, so as to have its walls always 
distended. Thus, if one drachm of blood is in a vessel, the 
vessel contracts so that it holds without distention less than 
a drachm. The presence of the drachm, therefore, causes a 
distention of the walls. 

This regulation of the caliber of the vessels is controlled 
by the muscular tissue in the walls of the vessels. The 
whole system of regulation is controlled by the vasomotor 
nervous mechanism. 

This regulation is in constant operation in the accom- 
plishment of the various functions of the organism. Through 



170 PHYSIOLOGY AND HYGIENE 

it, the supply of blood is concentrated in active organs of 
the body. Thus, after dinner a large supply of blood is 
needed in the stomach and intestines, and the arteries of 
this region are therefore dilated to their full capacity, and 
filled with an extra supply of blood. This extra supply is 
drawn from the quota of other regions, as the brain and 
limbs, which are in rather diminished activity at this time, 
the vessels in these parts contracting in proportion to their 
diminished contents. If, however, a man uses his brain 
actively or exercises vigorously at this time, the brain and 
limbs will keep their full supply of blood, and the stomach 
will not get the extra blood which it needs, and thus the 
process of digestion will not go on as it should. We all 
have an illustration of this process in the flushing of the 
face and beating of the arteries of the head during mental 
excitement. 

V. HYGIENE OF THE CIRCULATORY SYSTEM 

There is a saying among physicians that a man is as old 
as his blood vessels. Certainly, any man who has a weak- 
ened or diseased heart or unsound vessels is old before his 
time. He is less fitted for work of any kind, and is more 
susceptible to disease, than a sound man of his age. 

The care of these organs should be a simple thing. The 
regulation of the cii'culation and the action of the circula- 
tory organs are automatic, and do not need special attention 
or special exercise. If we eat plenty of food these organs 
will get their full supply of blood. When we exercise our 
muscles the heart is exercised at the same time. All that 
we have to do in the care of these organs is to avoid any 
practices which injure them or their function. We must 
never subject them to overwork, and we must avoid taking 
into the system all substances which interfere with their 
action and health, as alcohol or tobacco. 



CIRCULATION AND THE CIRCULATORY SYSTEM 171 

Overwork. The heart is a muscle, and becomes exhausted 
by excessive exercise. The more work we do, whether with 
the muscles or the brain or the digestive organs, the more 
work the heart has to do. If we do too much, the heart 
may give out, and then all the organs suffer, since it is to 
the work of the heart that they owe their constant supply 
of nutriment. 

Men in running races or in rowing not infrequently over- 
tax the heart by keeping up too long. A heart once worked 
to the point of giving out may never be sound again. 

The blood vessels also suffer from such strain. The walls 
of the veins may give way with the extra pressure and be- 
come varicose. 

Taking cold. Undue exposure may give rise to an affec- 
tion of the circulation known as taking cold. Sudden or 
prolonged exposure to cold contracts the peripheral vessels, 
i.e., those near the surface, and thus causes an accumula- 
tion or congestion of the blood in the interior parts of the 
body. This , congestion in the membrane of the nose or air 
passages may cause inflammation or a tendency to inflam- 
mation, and, as a result, we have, with perhaps some irrita- 
tion from without, a cold in the head (a coryza), .or in the 
chest (a bronchitis). ^ The same cause may give rise to an 
inflammation of the intestines and diarrhea, or an inflamma- 
tion of the lungs or of the pleural membranes (a pleurisy). 
Such conditions should be guarded against by avoiding sud- 
den exposure. People should not go from a hot room into 
the cold air without extra clothing. At the same time a man 
should not become too dependent upon coats and mufflers, 
else he will catch cold whenever he leaves them off. The 
best plan is to keep the house cool, sleep with open windows, 

1 Certain of the affections of the air passages which we call colds are undoubtedly- 
due to infections by microorganisms, and not merely to congestion of the parts. But 
susceptibility to these infections is increased by these congestions. 



172 PHYSIOLOGY AND HYGIENE 

take a cold morning bath, and keep warm when out by 
walking briskly. In this way one becomes hardened to cold. 

Hemorrhage. When a blood vessel is injured or cut, we 
liave a flow of blood known as a hemorrhage (Greek Jiaima, 
" blood," and regnumi, " I burst forth"). Where the wound 
is slight the flow will cease of itself, the openings of the 
vessels being closed by the clotting of the blood. This clot- 
ting is rapid in the blood of healthy persons. It is less 
rapid and complete in the blood of poorly fed people or 
people who drink much alcoholic liquors. 

Where the cut is deep or a large vessel is severed, the 
flow prevents clotting. In such cases pressure must be 
applied to the vessel above the wound. If the cut is in a 
limb a handkerchief should be bound or twisted tightly 
about the limb,— above the cut if the bleeding vessel is an 
artery, below if a vein, — and the patient should be brought 
to a physician. All cuts should be scrubbed with water 
which has been boiled, to prevent the setting up of inflam- 
mation there. The air and the soil are filled with minute 
bodies known as bacteria, which get into these wounds and 
irritate them, if the lesions are not carefully cleaned. 

Fdiuting occurs when the heart fails to pump the blood 
into the head. Such a condition may occur as a result of 
nervous shock which inhibits the action of the heart tem- 
porarily. When fainting occurs, the patient should be 
placed with tlie liead low, when the blood will soon return 
to the brain. 1 

The blood corpuscles carry the oxygen to the tissues. 

1 Tlie custom of gh-iiig a person who is faintine; a few sips of cold water is based 
upon the fact that sipping water qnickens the circulation, wliile ordinary drinking does 
not. During the act of sipping the action of the nerve which slows the beating of the 
heart is inhibited, and, as a consequence, that organ contracts much more rapidly, and 
the circulation in various parts of the body is increased. A child gets this same stim- 
ulation by sucking. Thus, when a child sucks its thumb after being scolded, it is get- 
ting itself cheered up by the increased circulatoiy activity induced — unconsciously, 
of course. 



CmCL^LATION AND THE CIRCULATORY SYSTEM 173 

This they do by means of the hemoglobin which they 
contain. 

One constituent of this substance is iron. We nmst be 
sure to have a supply of iron in the food, else the blood 
will suffer, and through this all the tissues will fail of their' 
full supply of oxygen. 

People who do not get sufficient food or the right kind 
of food suffer from a lack of corpuscles in the blood or a 
lack of iron in the corpuscles. This condition is called 
ancemia (Greek «, " without/' and liaima, " blood "). The con- 
dition may be due to overwork or impure air as well as poor 
food, as in these conditions the blood seems to be unable to 
gain sustenance from the food. In treating anaemia the 
endeavor should be to administer the iron in food rather 
than in medicines.^ 

The vitality of the body is directly dependent upon the 
purity and richness of the blood, and the capacity of the 
heart to keep this supply in active circulation throughout 
the parts. People whose blood is lacking in iron, or who 
have poisonous substances contained in the blood, are not 
strong and have diminished power to resist disease.^ 
Where the heart is weak the blood tends to stagnate in 
parts. It fails of sufficient aeration and becomes impure. 
The parts cannot get the food which they need, and do not 
repair actively. 

Germicidal power of blood. The blood of healthy indi- 
viduals possesses a certain power to kill or make inactive 

1 The ordinary diet contains a sufficient supply of iron for health. Some foods con- 
tain much more than others. Thus, milk, rice, potatoes, bread, and cereals contain 
small amounts. The following, which are given in the order of their richness in iron, 
are the leading iron-containing foods: spinach, asparagus, cabbage (outer leaf), beef, 
mutton, lamb, dandelions, apples, almonds, hazelniits, lentils, beans, carrots. 

2 Reports from the war between the Turks and the Greeks inform us that ^mong 
the former the wounded recovered fi-om the effects of severe injuries most marvel- 
o'lsly. Wliat is the reason for this .? One reason is the fact that the Turks are com- 
pelled by their religion to abstain from alcoholic drinks. This gives them a great 
advantage, for their blood is pure. — Journal of Hygiene, 1897. 



174 PHYSIOLOGY AND HYGIENE 

the germs of disease— a germicidal (Latin ceedo, "I kill"— 
''germ-killing") power. Tims, in every open wonnd, and 
even when we eat and drink, a certain number of harmful 
bacteria probably get into the blood. But the germicidal 
power therein destroys them (and no abscess in the wound 
or no disease of the body results). Where these germs are 
in large numbers, however, the blood may fail to resist 
them, especially where the blood is poor, or the circulation 
inactive. 

Leucocytosis (Greek leul'os, " Avliite," kutos, " cell," and suffix 
osis, " morbid state ") and phagocytosis (Greek phafjein, " to de- 
vour," and hdosj '' cell "). This germicidal power of the blood 
is helieved by some to rest in part in the white corpuscles. 
When a tissue is wounded or bacteria lodge anywhere, these 
little scavengers, the leucocytes, can be seen collecting to the 
point in great numbers. Some of the bacteria they eat up 
bodily. Others are killed pi'obably by substances which 
come from the corpuscles. If these little soldiers, plus the 
germicidal power of the serum, are strong enough, they stop 
or drive back the invading enemy at the very outset. Then 
other cells appear which build up a tissue wall against fur- 
ther advance. If the enemy are too many, however, the in- 
vasion goes on into the body, and the person contracts disease. 

Alcohol, when brought to act directly upon the heart, les- 
sens the force of the muscular contractions. Its action 
when brought to the heart through the general circulation 
cannot be so perfectly studied. There can be no doubt, 
however, that alcohol when taken into the system may cause 
disorder of the heart's function and even disease of its 
tissue. 

The common effect of alcohol drinking, whether developed 
by the action of the substance upon the central nerve cen- 
ters of the heart or upon the heart muscle itself, is to 
increase the rapidity and diminish the force of the heart's 



CIRCULATION AND THE CIRCULATORY SYSTEM 175 

action, so that the heart runs itself out like a mettlesome 
horse who is given the rein.^ 

A heart thus disordered in its action cannot endure so 
much strain as a sound heart. It will give out more easily 
with exertion or disease. It is a well-known fact among 
physicians that the heart of a patient who is addicted to the 
use of alcohol is much less able to withstand the extra strain 
imposed upon it by the existence of some severe disease, as 
pneumonia, than the average heart. 

Prolonged use of alcohol is very likely to cause a diseased 
condition of the heart, known as fatty degeneration. 

The use of alcohol appears to be an element in causing a 
change in the linings of the blood vessels, known as sclerosis 
(Greek sMeros, " hard "), which makes them hard and stiff 
and less able to do their pai-t in the circulation. The firm 
elastic and muscular tissues are replaced by less strong con- 
nective tissue. This change is frequently followed by a 
softening of the whole wall of the vessels, especially of the 
aorta and large arteries, known as atheroma (Greek atkera, 
'' gruel"). These changes cause weakening of the walls in 
places, where the pressure of the blood may force the wall 
out into a thin-walled pouch, or aneurism (Greek aneurunein, 
"to dilate"). These aneurisms are very serious affairs. 
They frequently burst and cause death of the individual. 

The dilation of the superficial vessels of the body caused 
by alcohol often becomes permanent with the constant use 



1 Even what is called moderate drinking has a much greater share than is generally 
supposed, not only in greatly increasing heart diseases in cases where they already 
exist, but also in inducing their development in the constitutionally and hereditarily 
predisposed to become affected by them. . . . Jxist as it happens that the dealers in 
horses ("runners out "), whose hearts are called upon to make oft-repeated and sudden 
exertions, are prone to become the \'ictims of heart disease, in like manner the oft- 
repeated sudden spurts of cardiac activity induced by the frequent indulgence in small 
quantities of alcohol lead, for precisely similar reasons, to equally deleterious conse- 
quences in persons already affected by heart derangement. — George Harley, M.D., 
F.R.S., London. 



176 PHYSIOLOGY AND HYGIENE 

of liquor. We are all familiar with the red-streaked ap- 
pearance of the face and nose which is often thus caused 
in drinkers. 

These various changes in the vessels which may foUow the 
use of alcoholic liquors make the man liable to the breaking 
or plugging of a vessel in his l)rain. This condition causes 
what is known as apoplexy, and is often the cause of sudden 
death. 

Tohdcco often produces derangement of the heart's action. 
Individuals who smoke, and especially boys, frequently 
suffer from rapid and irregular beating of the heart. They 
become easily exhausted. Their vessels become weakened 
and dilated. Smoking may bring on temporary failure of 
the heart's action, with fainting. Whether these effects are 
temporary or permanent, these organs and the whole sys- 
tem suffer from them, and their powers of resistance are 
lessened.^ This condition of " tobacco heart," which is very 
common in boys wlio smoke, will keep them from success in 
athletic contests. It will keep them from gaining admission 
to the army. In the examinations for enlistment during the 
recent war with Spain, many of the young men who pre- 
sented themselves were excluded owing to tobacco heart. 

DEMONSTRATIONS AND EXPERIMENTS 

1. An ox heart with a good "pipe" upon it, that is, with the large 
blood vessels cut at a distance from the heart, should be obtained from 
a butcher, and the anatomy of the organ studied. By cutting open the 
heart the four cavities, the valves, and the apertures may be made out. 

2. Study the effect of muscular exertion upon the rate of the heart 
action, by counting the pulse beats before and after running upstairs. 

1 Dr. Laban Dennis, of the New Jersey State Board of Health, reporting upon the 
effects of tobacco smoking upon the heart, says that it sometimes produces "irregu- 
larity, palpitation, a teeliug of oppression and faintness, with breathlessiiess and insup- 
portable pain in the region of the heart, which sometimes extends to the muscles of 
the chest and left arm. ' ' 



CIRCULATION AND THE CIRCULATORY SYSTEM 177 

3. Many of the phenomena of the circulation can be studied by 
means of a common Davidson syringe, or a syringe bulb with a short 
rubber tube upon the suction end and a long tube (six to twelve feet) 
upon the delivery end. Fit the long tube at the end with a glass tube 
drawn out to a fine caliber at the tip (a medicine dropper), to represent 
the resistance offered by the small blood vessels to the blood flow. 
Then spread the tube upon the table and force water through it by 
alternate compression and expansion of the bulb. 

The bulb represents the heart. At the suction end is a valve which 
allows the water to enter, but not to go out at that end, just like the 
tricuspid or mitral valves of the heart, so that when you compress it, 
all the water which has entered must flow on through the delivery end 
and the long tube. 

Note that though the water is thrown into the long tube in an inter- 
mittent manner by the successive compressions of the bulb, it flows 
from the end of the tube in a steady stream (the effect of the elastic 
walls of the arteries accomplished here by the use of an elastic rubber 
tube with an obstacle at the end). 

The same principle is applied in the fire engine, where the elastic air 
in the air chamber jolays the part of the elastic walls of the arteries. 

4. Attach a nonelastic tube (a glass tube) to the bulb by a short 
rubber tube. Note that here the flow will be intermittent, not con- 
tinuous. 

5. Compress the forearm for a short time. 

Note how the veins of the hand become distended by this obstruc- 
tion to their flow. Note also the little knots or swellings which appear 
in the course of the veins. These knots mark the locations of the valves 
of the veins. 

6. The circulation of the blood and the appearance of the capil- 
laries and the blood corpuscles can be studied in the web of a frog's 
foot or the tail of a tadpole placed under a microscope. 

Note the corpuscles flowing along. Note the walls of the capillaries. 
Note the cells of the walls. 



QUESTIONS 

I. What are the three objects accomplished by the circulation of the 
blood and lymph? Of what organs does this circulatory system con- 
sist? Where does the heart lief- What is the pericardium? De- 
scribe the heart. For what are the valves of the heart useful? Of 



178 PHYSIOLOGY AND HYGIENE 

what kind of tissue is the heart principally composed? What is the 
chief property of muscle tissue? 

II. By what is the heart action controlled? In what manner does the 
heart act? What causes the beat of the heart? What are the heart 
sounds? Describe the passage of the blood through the heart. Describe 
the action of the valves. 

III. What is the pulmonary artery? Wliere does the blood which is 
sent to the lungs go after it leaves the lungs ? Where does the blood go 
when it leaves the left ventricle? From what veins does the right 
auricle collect the blood? The left auricle? 

IV. What are the three classes of blood vessels? What is the aorta? 
Name and place some of the principal arteries. Name some of the large 
veins. What are the two subsidiary systems of circulation? What is 
the object of the pulmonary system? Of the portal system? 

V. Describe the structure of the capillaries. If you cut the wall of an 
artery it will not collapse; why? How is it with a vein? Describe 
the lymphatics. What does the lymph which they carry contain? 
Where is it made up? What are lymphatic nodes? 

VI. What is the thoracic duct ? Describe the method of the circulation 
in the vessels. What are the factors in keeping up the blood pressure? 
Of what does the x^ulse serve as an evidence? What is the force which 
causes the flow of the blood? What are the valves in the veins for? 

VII. What is meant by the vasomotor regulation of the circulation? 
Is there enough blood to fill full all the vessels in the body? What hap- 
pens in the vessels of the head and muscles when digestion is going on ? 
How can we exercise the heart? 

VIII. What is anaemia? How can we guard against it? What is 
taking cold? Has the blood any power to kill bacteria? 

IX. What is phagocytosis? Is the rapid beating of the heart which 
is caused by alcohol drinking good for it? What is tobacco heart? 
Suppose the semilunar valve of the heart to give way, what would 
happen to the blood which the heart forces into the aorta? 

X. What is the connection between exposing the surface of the body 
to cold air and a cold upon the lungs or in the head? 



CHAPTER IX 

RESPIRATION AND THE RESPIRATORY SYSTEM 

IN addition to food, the body has to be supplied with 
another substance, free oxygen. As we have explained, 
the body is kept going, like an engine, by the burning of 
the substances within it. Now, burning within the body or 
without is, as you know, a process of oxidation. In order 
that it may take place, there must be free oxygen present 
with which the substance to be burned may unite. In the 
furnaces the coal gets this oxygen from the air. In the 
body, likewise, the oxygen is obtained from the air. It is 
obtained by the process known as respiration, or breathing. 
The air is taken into the part of the body known as the 
lungs. Here the oxygen is separated from the air and car- 
ried by the blood about the body to the cells, which are the 
furnaces where the burning takes place, the seat of the true 
or internal respiration. 

Respiration (Latin re, ''again," and spirare, "to breathe") 
is accomplished by a set of organs known as the respiratory 
tract. This tract consists of the upper air passages, the 
mouth, nose, pharynx, larynx, trachea, and the lungs. 

The mechanism of respiration is secured by the muscular 
action of the walls of the thorax, plus the natural air pressure. 

Double object of respiration. The process of external res- 
piration serves a double purpose. It accomplishes, first, the 

179 



180 



PHYSIOLOGY AND HYGIENE 



importing of the free oxygen to the body ; second, the ex- 
porting or elimination from the body of certain waste prod- 
nets of tissne combustion, the carbon dioxide and water. 



I. THE RESPIRATORY TRACT 

The cliief organs of respiration are the hoigs. On its way 
to and from the lungs, the air passes through the H2)per air 

passages. The air en- 
ters these passages 
by the nose or month. 
The cavity of the 
mouth has already 
been described. 

The nose contains 
two cavities, sepa- 
rated by the nasal 
septum, the left and 
right nostrils. Each 
nasal cavity is par- 
tially divided into 
three chambei-s by 
the turbinate bones, which project into it. Behind, the 
nasal cavities open by the posterior nares into the pharynx. 
The air in passing through the nose is warmed. It gains 
moisture from the nasal membranes, and it is freed from 
dust and germs by the hairs which lie in the anterior 
nares. 

The pharynx is a funnel-shaped cavity which connects the 
nose and mouth cavities with the larynx and trachea. It 
has been described in the chapter upon the nutrition of 
the body. 

The opening to the larynx is a narrow slit called the 
glottis. It is covered by a cartilaginous lid, the epiglottis 




Liiiif's. 



RESPIRATION AND THE RESPIRATORY SYSTEM 181 



(Greek epi, " upon "—upon the glottis). This lid is open dur- 
ing respiration, but closed while food is passing the pharynx. 

The larynx is a cavity between the pharynx and trachea. 
It is the seat of the organ of voice, and will be described in 
the chapter upon the voice. 

The trachea (Greek tmchus, ''rough") extends from the 
larynx downward. Close to the lungs it divides into two 
tubes, the bronchi (Greek bronchos, " windpipe"), one for each 
lung. Each bronchus divides into numerous small bron- 
chial tubes, which divide again into still finer ones. Each 
fine tube ends in a cluster of short blind tube branches. Each 
cluster of dilated tube ends is 
called an mfundibiilum (Latin, 
" funnel "). Each infuiidibulum 
is divided into several chambers 
by an infolding of its wall. Each 
chamber is called an alveolus 
(Latin alveus, " a hollow vessel "). 

In the lung are immense num- 
bers of these infundibula with 
their alveoli, joined by connec- 
tive tissue. The fine bronchial tubes, of which these in- 
fundibula are the dilated ends, conduct the air to the alveoli. 

The lung may then be said to be made up of numerous 
branching tubes, the closed, dilated, and chambered ends 
of which are all bound together by (Tonnective tissue and 
inclosed in an elastic membrane, the pleural (Greek pleura, 
'side") membrane} 




Lung infundibula. 



1 The kings represent a contrivance for providing the body with as large a surface 
as possible for the absorption of the oxygen of the air. In small animals (insects) the 
surface of the body is so great in proportion to their bulk that the absorbent surface, 
provided by the external surface of the body, is sufficient for the needs of respiration, 
so that these animals need no special contrivance (no lungs) for this purpose. In 
higher animals extra sui-face is necessary. In fish this is provided by the gills. In 
air-breathing animals the lungs, with their thousands of little pits (alveoli), which 
greatly increase the surface included in a small space, are provided. 



182 



PHYSIOLOGY AND HYGIENE 




Ciliated cells. 



In structure the wall of the trachea consists of a connec- 
tive tissue framework containing plates of cartilage con- 
nected together by muscular tissue. Internally the tube is 
lined by an epithelial membrane. 
IS If Is? W '^^^ epitli«li">" lias as its surface 
m l')M if '^ \ri layer columnar cells bearing each a 
short, thin process. These processes 
are called cilia (Latin cilium, "eye- 
lash"). They are protoplasmic and 
are in constant motion, waving up- 
ward toward the mouth. By this 
action they drive any fluid which 
may collect in the trachea out toward the mouth. Similar 
cells exist in the larynx and nose, where they serve a similar 
purpose. 

The bronchial tubes have a structure similar to that of the 
trachea. The cartilage and muscle tissues are, however, of 
small amount here, and in the finer tubes they may be 
entirely absent. 

In the inf undibula and alveoli chambers the walls consist 
of fine elastic connective tissue covered by an epithelial mem- 
brane continuous with that of the bronchial tubes, of which 
they are the termination. The cells of the membrane in the 
alveoli are flattened. In the connective tissue about the 
cells runs a network of capillary blood vessels. 

As stated, the walls of the alveoli and the fine tubules 
contain much elastic tissue. As a result the lung is a very 
elastic organ. It can be distended by air to much over its 
natural size, but tends to return to this size and expel the 
air when the pressure is removed. 

The pleural membrane. The elastic connective tissue 
membrane, the pleura, which incloses each lung, leaves the 
viscus at the root, and, folding upon itself, lines the walls of 
the thorax, in which the lungs are placed. Eacli lung is 



RESPIRATION AND THE RESPIRATORY SYSTEM 183 

thus surrounded by a closed sac in the same manner as is 
the heart. 

The two free surfaces of this sac, which approximate each 
other, are covered with a serous membrane. This mem- 




Lung tissue. 

brane is moistened by a secretion from these cells. The 
surfaces of the sac thus slide easily over each other in the 
movements of respii'ation. 

n. THE MECHANISM OF RESPIRATION 

The function of respiration is regulated by the action of 
the walls of the thorax, under the control of the muscles 
which attach to or make up these walls. 

The thorax is a conical cavity surrounded by a wall of 
bone, cartilage, and muscle. The walls consist of the verte- 
bral column at the back, the ribs and the costal cartilages, 
with their fibrous tissue and muscles, at the side, the ster- 
num in front, and the large muscle, the diaphragm, below. 

HEWES, P. & H. — 12 



184 



PHYSIOLOGY AND HYGIENE 



Outside, this cavity is covered by muscle, fat, and skin. 
Inside, it is divided into a right and left cavity, each being 
lined by the serous membranes, the pleura. 

The bones of the thorax are all so articulated that, by 
movements of its skeleton, the shape of the thorax can be 
changed, and its cavity enlarged or contracted. 

Action of the diaphragm. The vertical enlargement of the 
thorax, the lengthening from top to bottom, is brought 

about by the large muscle 
called the diaplii'agm. This 
muscle forms the dome- 
shaped floor of the thorax. 
It consists of a central ten- 
don, from which striate mus- 
cle fibers radiate in all direc- 
tions. These fibers attach to 
the lower ribs, the sternum, 
and the vertebral column. 

When they contract they 
pull the tendon down to a 
lower plane, thus enlarging 
the thoracic cavity at the ex- 
pense of the abdominal below. 
Action of the intercostal mus- 
cles. The increase in the size 
of the thorax from front to back is brought about by the 
raising of the rib arches and sternum upon the spine. This 
action is controlled by the exiermd IntercostaJ (Latin inte7\ 
"' between," and cosfa, '' rib ") muscles, which run from rib 
to rib. 

During rest the ribs which pass around from spine to 
sternum, the first seven, run downward. Each rib thus 
forms an arch or hoop, with its front lower than its back. 
The fii'st arch at the top is the smallest. They then in- 




Diaphragm. 



RESPIRATION AND THE RESPIRATORY SYSTEM 185 

crease in size until the lowest, the seventh, is reached. 
When the intercostal muscles contract, each arch is brought 
into the place of the smaller one above it, and the front 
point of the thorax, the sternum, lies farther from the spine 
in each plane than before. The thorax is therefore en- 
larged from front to back. 

The raising of the thorax in this manner is accomplished 
by the contraction of each external intercostal muscle. 
The muscle from the first to the second rib contracts, and 
the second rib is pulled up, the first rib being held from 
coming down by ligaments and muscles above. The second 
muscle pulls on the third arch, and so on. These contrac- 
tions occur simultaneously, so that the whole thorax is 
moved as one piece. 

The mecJianism of inspiration (Latin in and spirare, " to 
breathe") takes place in the following manner: The elas- 
tic lungs lie in the closed thorax. Through the air passages 
the air from without reaches them and presses upon the 
walls, just as it presses upon the body surface. As there 
is no pressure about the outer walls of the lungs except 
the pressure of the chest walls, this air pressure drives the 
elastic walls out until they everywhere fill the chest cavity 
and press against these chest w^alls. Thus when at rest the 
lungs are distended as much as the walls of the thorax will 
allow. 

In inspiration the simultaneous contraction of the dia- 
phragm and intercostal muscles makes the thoracic cavity 
longer and deeper, that is, considerably larger, so that the 
walls of the lungs, which were held in by the thoracic w^alls, 
expand still further under the air pressure from within, fill- 
ing the larger cavity formed by the recession of these 
walls. In this way the lungs grow larger, and more air 
rushes in from without. The forces which govern inspiration 
are, then, muscular effort and atmospheric pressure. 



186 PHYSIOLOGY AND HYGIENE 

Expiration (Latin ejc and S2)irare, '' to breathe out ''). When 
the niuselos liave linished their contraction they relax, and 
as they do so, the walls tend to return to their old position. 
Tliis decreases the size of the chest cavity a^ain, and the 
walls of the lungs are pressed in by the incoming chest 
walls, the air being expelled through the air passages. 
This expiration in moderate breathing is due principally to 
the elasticity of the thoracic walls and lungs, which, when 
they are given a chance by the relaxation of the muscular 
tension, tend to return to their regular shape and position, 
driving out the air before them. 

In forced respiration the action of inspiration is aided by 
the action of other muscles which pass from the thoracic 
skeleton to the spine. That of expiration is reinforced by 
the action of the abdominal muscles and the internal inter- 
costal muscles, which lessen the regular size of the thoracic 
cavity. These nniscles act in causing the short forcible act 
of expiration known as a cough. 

Experiraeiit. The action of the lungs in expandinri: under air pressure 
can be illustrated by a rubber bag placed in a jar from which (he air 
can be exhausted. When the bag is opened it collapses, as the pres- 
sure of air is equal within and without, and the bag collapses by its 
natural elasticity. If the bag bo placed in a closed jar with a tube con- 
necting the bag with the outer air, and then the air in the vessel be 
exhausted, the bag will at once bulge out until it touches the walls of 
the jar. In this experiment the jar walls represent the thoracic walls, 
the bag the lungs. 

III. THE GAS INTERCHANGE IN RESPIRATION 

The object of the respiratory apparatus is to facilitate an 
exchange of gases between the body and the air. 

The air is breathed in rich in oxygen. In the lungs it 
gives up some of its oxygen for use in the body, and takes 
up an equivalent of carbon dioxide waste from the body. 



RESPIRATION AND THE RESPIRATORY SYSTEM 187 

It is then breatlied out a^ain. The expired air tlius differs 
in composition from the inspired air. It contains less 
oxygen and more carbon dioxide. 

The quantity of air inlialed aiid exlialed in each respiration 
is about thirty, cubic inches. The body therefore gets the 
benefit of the oxygen contained in this thirty cubic inches, 
and also of the carbon-dioxide-carrying capacity of this 
amount of air every time the action of breathing occurs 
(Experiments 2 and 3, pp. 194, 195). 

The oxygen which the inspired air loses in the lungs is 
taken up by the blood. In return the air in the lungs takes 
up a certain amount of carbon dioxide gas from the blood. 

This interchange of gases between the air in the lungs 
and the blood takes place through the walls of the lung 
alveoli and the blood capillaries. All about in the walls of 
tlie alveoli, in a network, lie these blood capillaries. They 
bring the venous blood, loaded with carbon dioxide waste, 
from the tissues to the alveoli walls. This gas waste is 
passed through the walls of the capillaries and of the alveoli 
as througli a fine sieve, and is taken up by the air. At 
the same time the free oxygen of the lung air is passed 
through these walls and taken up by the blood, so that 
the dark venous blood, which comes to the lungs rich in 
carbon dioxide and poor in oxygen, goes away as a bright 
scarlet arterial blood, poor in carbon dioxide and rich in 
oxygen, and is thus distributed over the body. 

The oxygen which passes into the blood is taken up there 
by the red corpuscles. These corpuscles contain a substance 
known as hemoglobin, which has a strong affinity for oxy- 
gen, combining with it to form a compound known as 
oxyhemoglobin. 

In the circulation each corpuscle with its load of oxygen 
thus loosely combined is carried to the tissues throughout 
the body. Here this oxygen is given up again and used in 



188 PHYSIOLOGY AND HYGIENE 

the tissues for combustion. It is this last step, this utiliza- 
tion of the free oxygen from the blood in the tissues, which 
is the real process of respiration, for the accomplishment of 
which all the other steps, the external respiration and cir- 
culation, are but a means. 



IV. THE EXCRETION OF WATER BY THE LUNGS 

In addition to serving as a means of gas interchange be- 
tween the body and the air, the respirator}^ function serves 
other purposes. One of these is the removal of water from 
the body. The expired air always comes out moister, that is, 
richer in water, than the inspired air. A certain amount of 
water is removed from the blood in this way. This exces- 
sive moisture of the expired air can be observed upon a 
frosty day. The air upon issuing from the mouth looks like 
a cloud of steam. The water which is taken up by the lung 
air at the body temperature of 98. 6° F. is deposited by con- 
densation in the cold air outside (Experiment 4, p. 195). 



V. THE ABDUCTION OF HEAT 

Respiration also serves for the removal of a certain 
amount of heat from the body. The air taken into the 
lungs upon a day when the temperature is at 70^ F. 
comes out with a temperature of 97° F. Thus just so much 
heat is removed from the body as there is difference in the 
inspired and expired air (Experiment 5, p. 195). 

The volume of the expired air is greater than that of the 
inspired, smce the air is expanded by the higher heat of the 
body and has also taken up water. Its gas volume, however, 
IS less, as it has lost 5.4 volumes of oxygen and taken up 
only 4.3 volumes of carbon dioxide. 



RESPIRATION AND THE RESPIRATORY SYSTEM 189 



VI. HYGIENE OF RESPIRATION AND THE RESPIRATORY TRACT 

The frame of the thorax and the muscles which control 
respiration are developed by vigorous out-of-door exercise, 
as running, rowing, and swimming. In inspiration the 
chest walls and the abdominal walls are driven outward. 
Tight clothing which interferes with this expansion, as tight 
corsets and tight belts, should be avoided.^ Breathlessness 
or rapid breathing is much more marked after exercise in 
a woman who wears tight corsets than in one who does not. 

The lining membranes of the air passages are easily irri- 
tated by the inhalation of fine, solid particles in the air, 
known as dust, or smoke. We should avoid working in 
atmospheres which are very dusty. We should keep our 
living rooms as free from dust as possible.^ 

Tobacco smokers are apt to contract a chronic relaxed 

1 " Ample lung capacity is vital capital. This cannot be secured with the muscles 
of respiration bound down by tight clothing. In addition to giving them room for free 
play it is well to add to their capacity by special exercises in breathing. One of the 
simplest exercises is full, deep breathing. ' Draw in a long, deep breath, expanding 
the chest as fully as possible without straining either lungs or muscles. Retain the 
breath thus taken while you count ten; then as slowly as possible expel it.' Or, 
' stand erect with chin down, and rise on the toes as you inhale ; hold the breath for a 
few moments, so that the air may act on the whole surface of the blood, nourishing it 
and at the same time taking up impure gases ; then expel it forcefully and as com- 
pletely as possible, coming down on the heels at the same time. ' 

"By such exercises the blood becomes saturated with oxygen, and the capillaries 
carry it to every part of the system, bathing every cell. . . . The lungs increase in 
elasticity, so that the chest expansion may be increased several inches, while the effect 
of these exercises reacts on every tissue of the body, producing a healthier tone and 
stimulating its growth." 

2 The would-be neat but unwise housekeeper, after sweeping her carpeted floor, 
whisks the dust from her furniture vnth a feather duster, satisfied if she but transfers 
it from regions seen to those imseen. Not so the hygieme housekeeper. First of all, 
she reduces dust to a minimum by discarding carpets and living on bare floors with 
plenty of rugs which can be taken outdoors and beaten. She dusts her smooth floor 
with a soft or damp cloth, and so does not raise a fog as in sweeping a carpeted room. 
She dusts her bric-a-brac with a soft cloth, which she shakes frequently out of the 
window. She lets in volumes of fresh air and sunshine, and when she has finished her 
room it not only looks clean, but it feels clean, smells clean, and is clean, 



190 PHYSIOLOGY AND HYGIENE 

condition of the membranes from this constant irritation, 
especially those who inhale the smoke.^ 

All influences which tend to congestion of the membrane 
of the lungs and air passages are to be avoided. Such in- 
fluences, for instance, are undue exposure to cold and in- 
dulgence in alcohol. It has been explained in a preceding 
chapter how cold may cause inflammation of the lungs or 
air passages. 

Alcohol^ when taken frequently, keeps the membranes of 
the lungs and throat relaxed. The circulation in the di- 
lated vessels is less active, and thus congestion and conse- 
quent inflammation are more apt to follow exposure in these 
cases than in healthy individuals. Such subjects suffer 
very frequently from pharyngitis and from bronchitis.^ 

Sore throats and coughs should be cared for at once, else 
the condition of the tissues may become chronic. When 
one has a cough he should not spit out what he raises upon 
the sidewalk or floor, but into appropriate vessels, as other 
people may contract the disease from the dried sputum 
lying or floating about. People with chronic coughs should 
live out of doors in dry country air. 

Ventilation. The air of a room with people in it is con- 
stantly losing oxygen and accumulating carbon dioxide and 
other substances excreted in the expired air. Some of these 

1 Habitual smokers are notoriously liable to colds in the head and to bronchitis and 
other congestive affections of the air passages. On this subject Dr. J. F. Rumbold 
says: " The congestion occasioned by the action of tobacco on the mucous membrane 
of the superior portion of the respiratory tract resembles in many respects the conges- 
tion resulting from the effects of a cold. Some of these are transitory and some per- 
manent. The local effects of tobacco on the mucous membrane of the siiperior portion 
of the respiratory tract causes a more permanent relaxation and congestion than 
any known agent." Tobacco depresses the system while it is producing its pleasur- 
able sensation, and it prepares the mucous membrane to take on catarrhal inflamma- 
tion from even slight exposure to cold.— British Medical Journal, 1880. 

2 Those who have injured themselves with alcohol show less power of resistance 
against influences unfavorable to healtli, and are carried off by diseases which other 
people of the same age pass through safely, especially in cases of inflammation of the 
lungs. — Birch-Hirschfeld. 



RESPIRATION AND THE RESPIRATORY SYSTEM 191 

excreted substances are poisonous, and if they are allowed 
to accumulate in any quantity will poison the people who 
breathe the air, causing headache, dullness, and exhaustion. 
So it is very important to prevent the accumulation of these 
products. To accomplish this prevention we must keep 
the room air constantly changing. This system of chang- 
ing the air of a building is known as ventilation. 

The carbon dioxide excreted by the lungs does not collect 
in amount sufficient to have a poisonous action, but the 
amount of it present serves as an index of the amount of 
poisonous impurities present. So by measuring the carbon 
dioxide in the air of a room we are able to tell whether the 
air is pure or impure. If the air contains two volumes car- 
bon dioxide in ten thousand volumes, air, we call it fresh. 
If it contains six volumes carbon dioxide it is impure. So we 
arrange our ventilation to keep the proportion of cai-bon 
dioxide in the air as much below six volumes as possible. 

Ventilation is best secured by bringing the fresh air in 
high up, and allowing the mixed air to escape by fireplaces 
or other ventilators. The fresh air may be brought in 
warm by hot-air apparatus, so as to avoid drafts of Qold air. 

It is important that the air should contain a certain 
amount of water. Very dry air takes too much water from 
the membranes of the air passages, and causes a consequent 
irritation of the tissues. Stoves in a room are likely to dry 
the air too much. Hot-air flues or open fires are better 
means of providing heat. 

The odor of the air is a guide to its condition. Wherever 
the air of a room smells close, ventilation should be applied. 

The constant purification of the air is carried on by plants. 
These organisms break up the carbon dioxide which collects 
in the air, and take up the carbon, leaving the oxygen free 
for the air. 

Not only is a continuous supply of oxygen essential to 



192 PHYSIOLOGY AND HYGIENE 

lifo, but any diiniiiution in tlie exchange of oxygen and 
carbon in the system lessens nerve sensibility and mus- 
cular force. Confinement in close rooms is probably, in 
cases, a predisposing cause of consumption, which numbers 
far more victims than any other one disease in our temperate 
climates. Probably a nuijority of all the families in the 
country live all winter shut up in close, heated rooms, with 
the life giving oxygen (carefully shut out, and poisonous 
vapors as carefully shut in. 

" Live as much as you can with open windows, wearing 
whatever extra clothing is necessary. If you cannot bear 
an open window, even with an extra coat and a rug over 
your knees, when you are sitting in a room, do the next 
best thing, wliieh is to throw the windows wide open, and 
take some active exercise for a few minutes, while the air 
in the room is being swept out and fresh air coming in to 
take its place.'^ Avoid chill, but at the same time avoid im- 
pure air. In a room where no means of ventilation are 
furnished, as is usually the case, there are various simple 
ways of keeping the air constantly changing without lower- 
ing the temperature too much or creating a draft. One is, 
where there is an outside door in the room, to fasten a chain 
upon it with a hook on the opposite side, over which the 
links of the cluiin may be thrown. The door may then be 
opened an almost imperceptible crack, or an inch, or half 
an inch, according to the weather. A screen can be set in- 
side the door to shut off any draft, if there be any. Or the 
lower sash of a window nuiy be raised a few inches and a 
piece of perforated zinc placed in the open space. The foul 
air will go out through the zinc and the fresh air come in 
between the sashes with an upward current, and the latter 
will thus become warmed before it circulates through the 
room. 

Sleeping room ventilation is also an important matter. 



RESPIRATION AND THE RESPIRATORY SYSTEM 193 

These rooms should be lar^e and well lighted, and some 
means devised for securing* a constant change of air without 
direct draft during the night. In the morning tlie windows 
should be thrown wide open as soon as the room is vacated, 
the sheets and blankets should be taken off one by one, 
shaken, and spread out to air, and the room left for at least 
an hour with the air and sunlight pouring in before the bed 
is made up. Blankets that can be washed are the only 
suitable bed coverings ; mattresses should be pulled apart, 
cleansed, and made up with new covers every few years. 
The furniture should be plain and simple, and such as can 
be kept free from dust. 

Tonsils. There are certain parts, in struts ture like that 
of lymph nodes, present in the throat, known as tonsils. 
Where these are large they may interfere with respira- 
tion. 

Adenoids (Greek aden, '^a gland," and eidoi^, "like"). 
Some people have growths of tissue in the nasopharynx 
known as adenoids. Large tonsils or adenoids tend to 
obstruct the air passages and thus to interfere with respira- 
tion. The adenoids, obstructing the posterior nasal openings, 
tend to cause mouth breathing, which is not so good <is 
nasal breathing. When a child breathes with the inouth 
open, adenoids should be suspected.^ If large tonsils or 
adenoids are allowed to remain in children they may affect 
the development of the lungs and thorax. They make the 
middle ear more susceptible to disease by affecting its air 
supply through the Eustachian tube. They therefore should 
be removed earl}^ 

' People of all ajsjes need to know that it is necessary to keej) the month shnt, for 
it was not intended for breathing x)nr])<)ses, the nose being essential to this purpose 
and having the advantage that it warms the air and strains from it irritating matters 
in.inrious to the lungs. Remember the mouth is exclusively iieeded as a port of entry 
for food and a port of exit for crystallized thought, the chief medium of communica- 
tion between man and man. — Journal of the American Medical Association, Novem- 
ber 2U, 1S97. 



194 PHYSIOLOGY AND HYGIENE 

It is an excellent habit to rinse the mouth and throat every 
morning with warm water or salt and water. 

Asphyxia. When the blood cannot get oxygen the person 
is said to be asphyxiated. Such a condition occurs where a 
person is smothered or suffocated by smoke or illuminating 
gas, or is drowned. 

Drowning. A drowning person has lost the oxygen from 
his lungs and blood. The heart and lungs have therefore 
ceased to work, as neither circulation nor respiration can go 
on without free oxygen. To resuscitate a man who has 
been exposed to drowning we must first place him on his 
face, with his head low, to let the water run out from his 
lungs. Then apply warmth about him and start the respi- 
ration by artificial means. 

Artificial respiration. The person is placed upon the back, 
with clothes removed. The arms are lifted straight above 
the head and then lowered again to the sides, pressing in the 
thorax. This motion should be made regularly about eigh- 
teen times a minute. Unless the patient has gone too far the 
respiration will return in time and the circulation start up. 

DEMONSTRATIONS AND EXPERIMENTS 

1. Each pupil should demonstrate the presence of the air cavities in 
his thorax by placing one hand tiat upon his chest wall and striking the 
back of his fingers lightly with the midfingers of the other hand. A 
sound such as is obtained by striking the walls of a box or of any re- 
ceptacle filled with air will be heard. Contrast this with the sound 
obtained by percussing (as above) the skull. 

Note the movements of the abdomen and of the chest walls in res- 
piration. 

2. Repetition of Experiment 6, page 34. 

Place some limewater in a bottle. Exhale for several minutes 
through a glass tube which enters this liquid. The limewater will be- 
come turbid owing to the carbon dioxide which comes into it from the 
air which you exhale. This carbon dioxide unites with the calcium of 



RESPIRATION AND THE RESPIRATORY SYSTEM 195 

the limewater to form a white substance, calcium carbonate, which, 
makes the limewater turbid. 

3. Weigh out 8.7 ounces of charcoal. This represents the amount 
of carbon waste which the body gets rid of through the lungs daily in 
the form of carbon dioxide. 

4. Breathe upon a mirror. 

The moisture which condenses here comes from the exhaled air, 
which this demonstration shows to be charged with more moisture than 
the air without. 

5. Place the hand before the mouth. 
Note the warmth of the breath. 

Hold a delicate thermometer in front of the mouth. The mercury, 
which has perhaps stood at 70° (the room temperature), will mount rap- 
idly, showing evidence of the heat which comes out with each exhalation. 

6. The principle of the mechanism of respiration can be illustrated 
by the following apparatus : 

Remove the bottom from a bottle. Stretch a thin sheet of rubber 
tightly across the opening to cover it entirely, and bind it in place. 

Attach a stick to the center of this rubber sheet. 

Take a cork with two holes in it fitted to the top of the bottle. 
Through one hole run a glass tube with a collapsed toy balloon attached 
to its lower end. Through the other hole run a glass tube with a rub- 
ber tube attached to its upper end. On the rubber tube place a pinch 
cock. Insert the cork tightly so that the balloon lies within the bottle. 

Draw some of the air from the bottle by sucking through the rubber 
tube. This exhaustion of the air inside will cause the rubber sheet to 
arch upward. Close the rubber tube by the pinch cock. 

Then draw down the rubber sheet by the stick. As it descends the 
balloon will begin to fill out (expand). 

The balloon here represents the lungs, the rubber sheet the diaphragm. 

7. To demonstrate the circulation of air in a room. 

Pour some concentrated hydrochloric acid into an evaporating dish. 
(Be careful not to inhale the fumes.) 

Pour some ammonic hydrate into another dish. 

Bring the dishes near together. 

Note the fumes that form. Note the course which they pursue. 

Try this experiment in several parts of the room to study the 
direction of the air currents therein. 

Record air pressure in the mouth— its strength and direction (upon 
manometer)— in quiet inspiration ; in expiration ; in forced inspiration ; 
in forced expiration. 



196 PHYSIOLOGY AND HYGIENE 



QUESTIONS 

I. For what purpose does the body need free oxygen? By what pro- 
cess is it obtained? What other useful purpose is accomplished by 
external respiration? Describe the respiratory tract. What happens 
to the air in the nose ? What is the use of the epiglottis ? In what do 
the air passages end? 

II. Describe the lungs. What is the function of the ciliated cells of 
the trachea? What is the use of the cartilage in the tracheal walls? 
Of the elastic tissue in the walls of the finer bronchi? Describe the 
mechanism of respiration. What is the great muscle of respiration ? 

III. Describe the structure of the thorax, and show how the size may 
be increased by muscular action. What are the physical forces which 
govern inspiration? Expiration? Forced expiration? How is the air 
changed in the lungs ? In composition ? In moisture ? In temperature ? 
Of what is air composed? What does the blood obtain from the air m 
the lungs? What does this air obtain from the blood? If the lungs 
were shut off from the circulation what color would the blood in the 
arteries assume? 

IV. How does the blood carry the oxygen? Where is the seat of 
the real body respiration? How do we get rid of water by breathing? 
How do we get rid of heat? Can you ever see the water which comes 
out in the air from the lungs? 

V. What is apt to be the result of smoking upon the tissues of the air 
passages? What would happen to the air of a room full of people if it 
were not constantly renewed from without? What are the best methods 
of ventilating a room? To what agency do we owe the piu'lfication of 
the air in natural conditions? How should sleeping rooms be ven- 
tilated? 



CHAPTER X 

WASTE AND EXCRETION-THE EXCRETORY ORGANS 

WE have seen that the activity of the living organism 
is kept up by energy which is supplied by the oxida- 
tion of the living tissues. As a result of this combustion 
certain waste substances are formed in the body, just as 
waste substances, ashes and smoke, are formed when coal 
is burned. These waste substances are low chemical com- 
pounds of the elements which make up the tissues, carbon, 
oxygen, hydrogen, nitrogen, and so forth. They are princi- 
pally carbon dioxide (CO2), water (H2O), and nitrogen. The 
nitrogen, before excretion, is formed in the body into a com- 
pound known as urea, and excreted as such. 

The waste products have to be disposed of. Just as the 
ashes of a furnace must be taken out, or they clog the 
furnace fires, the waste substances must be removed from 
the tissues and the body, or they would clog the burning in 
the tissues. To provide for the disposal of these sub- 
stances is the work of certain organs called excretory (Latin 
eic, " from," and screo, '^ I hawk ") organs. They are princi- 
pally the lungs, the kidnej^-s, and the skin. 

Excretion of waste. The waste products are taken from 
the tissues by the lymph and blood. By the blood they are 
carried to the organs mentioned, and there separated from 

197 



198 



PHYSIOLOGY AND HYGIENE 



the blood and passed out of the body. The process of the 
elimination of waste products is called excretion. 

Of the waste products, the carbon dioxide is removed 
from the body by the lungs; the water by the lungs, skin, 
and kidneys ; the nitrogen waste, the urea, by the kidneys. 

I. EXCRETION BY THE LUNGS 

The process of the elimination of the carbon dioxide 
and water by the lungs in the function of respiration has 
been described in the preceding chapter. 



II. EXCRETION BY THE KIDNEYS 

The kidneys lie at the back of the abdominal cavity, one 
on each side of the lumbar vertebrae. Each kidney is a dark- 
red organ, about four inches long by two and a half broad, 

and one inch thick. The inner 
border of each is concave, the 
outer convex. Into this concave 
notch, or hihis (Latin, " a trifle "), 
of the inner border the artery of 
the kidney enters, and from it 
the vein leaves. From this same 
hilus the ureter, or discharge ves- 
sel of the kidney, proceeds. 

Structure of the kidney. The 
kidney is a gland of a very com- 
plex structure. If we open a kid- 
ney we see that the cut surface 
appears to consist of two parts, 
a cortical (Latin cortex, ^^bark") 
part and a medullary (Latin medulla, "marrow"). The med- 
ullary portion appears to be made up of a number of conical 




Section of a kidney. 



WASTE AND EXCRETION 



199 



portions, the pyramids, which protrude into a sacculated por- 
tion, the pelvis (Latin, " basin ") of the kidney. From this 
pelvis runs the ureter, or discharge pipe. In minute struc- 
ture the kidney consists of very small tubes lined with epi- 
thelial cells, about which are arranged, in a network, blood 
vessels and lymphatics. The whole mass is held together by 
connective tissue and surrounded by a firm capsule (Experi- 
ment 3, p. 212). 

The arteries from the main artery at the hilus run among 
the tubes and ramify into fine branches in the cortex. 
These branches end in fine clusters of capillaries known as 
glomeruli. From each of these clusters a vein issues. Each 
cluster of capillaries, or glomerulus 
(Latin glomus, '' a ball of cotton "), 
is suiTounded by the closed, dilated 
end of a tuhule (" small tube "). The 
whole structure, the cluster of ves- 
sels projecting into the closed end 
of a tubule, is known as a Malpighian 
(after Malpighi, who first described 
it) capsule. 

The wall of a tubule consists of 
a single layer of epithelial cells, 
mostly cubical in shape. The tu- 
bule begins at its closed, dilated 
end about a glomerulus. From 
here it proceeds by a tortuous course 
to the medulla, joining with other 
tubules and forming straight tubes 
which run parallel in the medulla 
and end at the pelvis. The water 
and some of the waste substances of the blood running in 
the glomerulus capillaries are separated from the interior of 
the tubule by the walls of the capillaries and the wall of 

HEWES, P. & H.— 13 




Diagram of kidney circu- 
lation, showing a glo- 
merulus and tubule, 

a, artery briuging blood to 
part ; b, capillary briuging blood 
to glomerulus ; h', vessel continu- 
ing with blood to tubule ; c, vein ; 
t, tubule; G, Malpighian capsule 
and glomemlus. 



200 



PHYSIOLOGY AND HYGIENE 



epithelial cells which lines the closed end of the tubule sur- 
rounding the glomerulus. Through these thin layers of cells 

the waste substances pass into 
the tubules. 

Below the capsules the blood 
capillaries run in a network 
about the tubules, and from 
these lower capillaries the urea 
is separated into the tubules, 
just as is the water above. 
Together these waste prod- 
ucts are borne along the tu- 
bules to the pelvis of the 
kidney. 

The separation of these prod- 
ucts is due to the specific action 
of the living cells which line the 
tubule. These waste substances 
are taken from the blood, 
while other useful substances, 
as albumin, are left behind. 

Urine. The amber-colored 
liquid which is thus formed by the separation of waste 
materials from the blood by the kidneys is called iirine. 




The kidneys and bladder. 

X, X, ureters. 



III. EXCRETION BY THE SKIN 



The skin is made up of two layers. The outer layer, the 
epidermis (Greek ejn, '' upon," and derma, " skin ") or cuticle, 
is formed of several strata of cells. The inner stratum con- 
sists of columnar cells, over this are several layers of round 
cells, and over these two strata are several layers of flat- 
tened cells, which, as you approach the surface, become mere 
scales. The outer stratum consists of dead cells which have 



WASTE AND EXCRETION 



201 




Section of skin of 
negro. 



lost their nuclei and become cornified or hardened. It is 
called the horny layer. The scales of this layer are con- 
stantly wearing away and peel off with 
friction, while new cells are being con- 
stantly added from the inner layers. 
This outer layer may be separated 
from the inner, as in the case of a 
blister (Experiment 1, p. 212). 

The deeper strata of the epidermis 
make up the Malpighian layer. 

The deeper layer of the skin is called 
the dermis, or corium. It is composed 
of a network of connective tissue, 
containing white fibers and yellow 
elastic fibers. The surface is raised 
into numerous elevations called pajjiUce (Latin, "nipples")- 
Some of these papillae contain clusters of blood vessels ; 

others contain the nerve organs of 
the sense of touch. This layer of 
skin is well supplied with blood 
vessels and nerves. A cut through 
the epidermis alone causes no bleed- 
ing. A cut into the dermis bleeds. 
The dermis rests upon the deeper 
tissues of the body, muscle and 
bone. It is separated from these 
by a loose tissue known as subcu- 
taneous (Latin sub, "beneath," and cutis, "skin") tissue. It 
is in this tissue that much of the fat in fat people lies. 

The dermis contains several special structures. These are 
the hairs, the sebaceous glands, the sweat glands. 

The hair. Hairs are found all over the body surface ex- 
cept on the palm and sole. Upon the head the hairs grow 
long. Over most of the body they are short and very fine. 




Section of the skin 
showing the roots of the 
hairs and the sebaceous 
glands. 



202 



PHYSIOLOGY AND HYGIENE 



Each hair is made up of a column of flat cells, like those 
in the epidermis, with a central shaft. It lies in a pit lined 

with epidermal cells and situated 
in a special papilla of the dermis. 
This pit' is the hair foUicJe (Latin 
foJlis, " a bag "—a little bag). The 
cells at the base of the follicle form 
the root of the hair. The hair grows 
\' W' \^ ^.\ IH /Ali)^^^ ^y ^^^^ multiplication of these cells. 
As nevv' cells form the older ones are 
thrust upward and become corni- 
fied, forming the column of the 
hair. 

The sebaceous (Latin sehiDn, 
^^suet") glands are small racemose 
glands consisting of clusters of cell- 
lined tubes with a duct opening into 
the follicle of a hair. The secretion 
of these glands is of a fatty nature ; 
it keeps the skin soft. 

The principal structures of the 
skin which carry on excretion are 
the siveat glands. Each sweat gland 
is a blind tube, the inner end of 
which lies coiled in a knot in the 
dermis. These tubes, starting from 
this coil, run in a corkscrew course 
through the epidermis and open 
upon the surface. The openings 
are called the pores. Each coil and 
tube is lined with a single layer of 
cubical cells. About the coil run 
blood vessels. From the blood in 
these vessels the glands separate 




Hair and hair follicle, 
with sebaceous gland en- 
tering follicle. 

h, hair ; s. sebaceous gland ; 
w, wall of f oUicle ; /, fat tissue. 



WASTE AND EXCRETION 



203 




certain substances, as water, inorganic salts, and organic 
matter, wliich are discharged as an alkaline fluid called stveat 

Perspiration (Latin jje/-, "through," and spirare, "to 
breathe"). This elimination of sweat is known as perspira- 
tion. The total amount of 'sweat in twenty- 
four hours is from twenty-five to seventy 
ounces (one and a half to four pints). Ninety- 
nine per cent of the sweat is water. The 
function of perspiration removes princi- 
pally heat and water from the body. 

Elimination of heat. The perspiration 
eliminated to the surface of the body evap- 
orates, and the water thus turns from a 
liquid to a vapor. In this change heat is 
taken up from the body by the water in 
becoming a vapor, and removed with it into 
the air. In ordinary conditions the amount 
of perspiration is comparatively small and 
evaporates from the pores, so that it does 
not appear upon the body. Such perspira- 
tion is called msensible ^ (Latin m, "not," and 
sentire, " to perceive "). In hot weather or 
after exertion the sweat pours out more rapidly than it can 
be evaporated, and collects in a perceptible moist layer or in 
drops upon the body surface. This is called sensible perspi- 
ration. By this large flow and evaporation of sweat much 
heat is removed from the body. The increase of sweat is 
assisted in these conditions by dilatation of the peripheral 
vessels and increased flow of blood to that part. Likewise 
in cold weather, when it is desirable to lessen the elimination 
of heat as much as possible, the vessels are constricted and 

1 The evidence that insensible perspiration is going on continuously can be obtained 
by placing a rubber cot upon the finger upon going to bed. In the morning, upon 
removing the cot, the finger will be found to be moist and swollen with the perspira- 
tion which has been prevented from evaporation. 




Sweat gland, 

with duet. 
d, duct ; g, gland. 



204 PHYSIOLOGY AND HYGIENE 

tlie ilow of blood to fclie skiii lessened. The secretion rises 
with this increased flow, but is not absolutely dependent 
upon it. It is regulated by nerve control. 

The nails. The nails consist of epidermis of the outer 
layer of horny cells formed into a plate. The nail lies in a 
bed of corium, called its matrix (Latin viater, "mother"). 
This portion is ver^^ vascular. Here new epidermal cells 
form, by which the outer cells are pushed out and thus the 
nail grows. 

IV. EXCRETION BY THE INTESTINES 

The egesta from the intestinal tract, the faeces, consist of 
the excretions of the liver and other glands, of the waste 
substances separated from the walls of the alimentary tract 
during digestion, and of the undigested elements of the food. 



V. HYGIENE OF EXCRETION AND THE EXCRETORY ORGANS 

The removal of waste is absolutely essential to the con- 
tinuance of health. If the waste products of muscular action, 
digestive action, brain action, are allowed to accumulate in 
the body, they will interfere with the liealth and function 
not only of these special organs, but of the whole body. We 
must do all that we can to accelerate excretion. 

Tlie attention must be directed first to keeping up a good 
circulation, since it is by circulation that the waste products 
are carried from the tissues to the excretory organs. The 
circulation is kept active by exercise and baths. In indolent 
people the circulation is apt to become sluggish, and the 
accumulation of poisonous waste resulting frequently in- 
creases the indolence. It causes dullness, drowsiness, and 
headache. The muscles become easily exhausted. The nu- 



WASTE AND EXCRETION 205 

triti()u of the tissues becomes unhealthy. Such people not 
only do not feel well, but tlie}^ are less able to resist disease. 

In the second place, we must keep the excretory organs 
in good condition. We must drink plenty of water to keep 
the kidneys flushed and to prevent concentration of the 
urine. A concentrated urine contains much solid matter in 
proportion to its water. It may irritate the renal tissues, 
its passage causing inflammation. It may tend to deposit 
its solids in the course of its passage, giving rise to the 
condition known as gravel. 

All substances which tend to irritate the kidneys should 
be avoided. 

People who keep their kidneys under constant irritation 
by indulgence in alcohol are apt to develop a chronic disease 
of the kidneys, chronic nephritis {(^veok nephron, "kidney")- 

When the kidneys give out, man}^ waste products collect 
in the body and poison the organism. This condition is 
known as urcemia. 

The care of the sMn consists in proper bathing and proper 
clothing. The excretion of the skin, the perspiration, in 
evaporation leaves its solid matters crusted on the skin. The 
sebaceous excretions tend to collect there. Dirt also gets on 
from without. All these substances tend to obstruct the pores 
and thus to interfere with the excretory action of the skin.^ 

Baths. The skin should be bathed daily. A cold sponge 
bath is preferable for those with whom it agrees. This bath 
clears away the deposits and causes a contraction of the pe- 

' Water is the vehicle in which are carried in solution the ingredients of tissue 
waste which the system is trying to get i-id of. The flow of water through the kidneys 
to the bladder furnishes a current in which to carry off the dissolved detritus ; there- 
fore the drinking of a physiological amount of water is a benefit and not a detriment 
to the kidneys. 

2 Exercise in the open air improves the appearance of the skin and is necessary to 
all who would have fine complexions. And yet exercise and bathing are not all. If 
the diet and digestion are bad the complexion will suffer. Fruits help to keep the 
system clean internally and to prevent the accumulation of waste matter which gives 
the skin an unwholesome appearance. 



206 PHYSIOLOGY AND HYGIENE 

ripheral (surface) blood vessels, which is followed by a dilata- 
tion and an increased flow of blood to the surface. In this 
way the circulation is stimulated. Those wlio do not react, 
that is, feel a healthy glow, after a cold bath would better use 
a warm one. Too long exposure to a cold bath will weaken 
instead of brace the system. Soap should be used upon the 
hands and the parts exposed to external dirt. A soap bath 
is not necessary of tener than once a week. The scalp should 
be washed every two weeks. Do not bathe while perspiring 
freely. 

Clothing. The skin should be kept at as even a tempera- 
ture as possible. The best clothing to wear next the skin 
should therefore be made of a substance which is a poor 
conductor, as wool. This will keep the body heat in. When 
the temperature without is high, as in summer, we can use 
cotton clothing, which conducts more readily. One must be 
careful about undue exposure in changing the thickness of 
the clothing. 1 

Regularity of the bowels. Tlie eliminations from the intes- 
tines (faeces) consist principally of waste tissue substances 
and the undigested residue of food. If these substances re- 
main stored up in the intestines they poison the system and 
are a menace to health and comfort. In a large proportion 
of people who feel run down, suffer from headache and nerv- 
ous disorders, the trouble is secondary to constipation. 

The bowels should move daily. Nature perfects most 
processes by forming habits in their regard. The bowels 
should be made accustomed to move at a regular time daily, 
and they will soon acquire this habit. 

1 People, and especially children, should dress according to the weather, and not ac- 
cording to the season. In winter woolen night garments are better than cotton, which 
may cause too sudden a change in the body temperature. Mackintoshes should not be 
worn without some other wrap underneath, as they hold in tlie heat and keep the body 
warm in some places and expose it in others, especially about the arms, which are 
sensitive. In this way they may predispose to pneumonia. " Mackintoshes and pneu- 
monia are twins, ' " one physician declares. 



WASTE AND EXCRETION 207 

Much constipation is due to improper dieting, improper 
modes of dress, and improper habits in regard to exercise. 
Plenty of bread, green vegetables, and fruits must be in- 
cluded in the diet list. Where a tendency to constipation 
arises it should be counteracted by the addition of more 
fruit and vegetables to the diet, especially such fruits as 
prunes, figs, tamarinds, and berries. Graham bread is pref- 
erable to white in such cases. A glass of warm water upon 
rising in the morning may prove helpful in this regard. 

Indolent habits tend to promote sluggishness of the 
bowels. Horseback riding or running and rowing are ex- 
cellent means of counteracting this sluggishness when it 
exists. 

Tight belts and clothing which binds about the waist tend 
to produce sluggishness of the bowels. Habits of regu- 
larity, diet, exercise, should all be tried before medicines 
are resorted to for the relief of constipation. When once a 
person begins using drugs to combat conditions which are 
the result of improper habits and negligence, he is giving 
hostages to health. The drug habit once fastened upon his 
shoulders will stay there like Sindbad's '' Old Man of the 
Sea." The right method is to discontinue the evil habits. 

The disposal of body waste. The proper disposal of the 
excretions, especially of the urine and faeces, is a matter of 
great importance. If not disposed of in the proper way 
these excretions will prove a source of contamination and 
disease to the community. 

Many diseases are essentially filth diseases, and their 
spreading, even their occurrence, can be controlled by proper 
sanitary regulations. Such a disease is yellow fever, which 
has played such havoc in Cuba. Several of the infectious 
diseases common with us, as typhoid fever, are transmitted 
through the excretions, and their existence can be abso- 
lutely stamped out in communities by proper care. The 



208 PHYSIOLOGY AND HYGIENE 

bacteria which are the cause of typhoid fever are present in 
great numbers in the excreta of persons suffering with 
this disease, and if these excreta are not disinfected, but 
are thrown into ordinary- earth closets or into those which 
empty into streams and I'ivers, a widespread epidemic of this 
disease may arise from a single case. The people living 
downstream may contract the disease by drinking the 
water.i Tj^^ drainage from the earth closet carrying the 
disease germs may sink into a well. The water of this well 
maybe used to wash milk cans by some farmer who supplies 
a village Avith milk, and the germs thus get into the cans 
and into the milk, and thus an epidemic of the disease run 
through the families who buy the milk. Typhoid fever may 
be also spread by means of flies, as occurred in some of our 
camps during the late war with Spain. The bacteria are so 
minute that a single fl}^ could carry away upon its foot as 
many as there are shingles upon tlie roof of a house. ^ 

All excreta from people suffering with contagious diseases 
should be thoroughly disinfected by chlorinated lime or some 
other disinfectant, or burned or buried, and all excreta, 
whether in health or illness, should be disposed of in proper 
closets where no flies can obtain access, and where they 

1 The mistaken notion that a running stream will rid itself of noxious substances 
should no longer he entertained where life and health depend iipon absolutely pure 
drinking water. — Seventeenth Annual Report of the New York State Board of 
Health. 1897. 

The same report says also that official approval should be withheld " from any pro- 
posed sewerage system which does not provide for other disposal [of sewage] than 
into any stream which, in any part of its coiarse, may be used for drinking purposes." 

^ It has been demonstrated that the germs of typhoid fever, cholera dysentery, and 
camp diarrhea are present in the discharges of those suffering from these diseases, and 
the pi-opagation of these infectious camp diseases results to a large extent from failure 
to properly dispose of excreta. No doiibt typhoid fever, camp diarrhea, and probably 
yellow fever are frequently communicated to soldiers in camp through tlie agency of 
flies, which swanu about fecal matter and filth of all kinds deposited upon the ground 
or in sliallow pits, and directly convey infectious material, attached to their feet or 
contained in their excreta, to the food which is exposed while being prepared at the 
company kitchens, or while being served at the mess tent. — Sanitary Recommenda- 
tions of Surgeon-General Sternberg. 



WASTE AND EXCRETION 209 

cannot drain into wells or running streams that are used 
for drinking water. 

In cities and towns with proper sanitary regulations all 
wastes are carried away by sewers to proper places of dis- 
posal. In the country and in villages where such an arrange- 
ment does not exist, the greatest care should be observed 
in the disposal of excretory matter, that it may not con- 
taminate the air or the water supplies. Cesspools should 
be abolished. Earth closets should be used, into which 
should be thrown daily a quantity of dry earth and the 
whole frequently removed.^ 

House sweepings and kitchen refuse should be burned, 
and all slop water containing matter capable of causing 
disease should be disinfected with chlorinated lime. 

VI. THE BODY HEAT 

The human body is nearly always warmer than the things 
about it. This is due to the fact that heat is constantly 
being produced in the body. This production of heat comes 
from the combustion of the tissues and their stores of food. 
When energy is liberated by the breaking down of any 
substance, as in the burning of the tissue of man or the 
wood tissue of a tree, this energy may take several forms. 
When the wood is burned outside the body the energy 
liberated takes the forms of heat and light. When the tis- 
sues are burned in the body the energy liberated takes the 
forms of heat and work. From four fifths to five sixths of 
the energy liberated in the body goes to heat. 

1 The contents of such closets are sometimes used on land for fertilizers. This 
should never be done where gi-een vegetables for human consumption are to be raised, 
as disease germs still retaining their vitality have been found thus disseminated on the 
vegetables so raised. Instinct teaches animals like tlie cow and horse to shun the herb- 
age, however luxuriant, that grows about their own excretions. Man's intelligence 
ought to read in this nature's warning against retaking into his system the wastes that 
have been thrown out for deeomjjosition. 



210 PHYSIOLOGY AND HYGIENE 

This heat is being produced coutinuously, since the tissues 
are continuously burning. The burning, and consequently 
the production of heat, is more active during marked activit}^ 
of the organs, as with muscular exercise or excessive mental 
work ; but it is going on all the time, as the heart is beating 
and the blood circulating and the cells secretiDg. This heat 
is distributed over the body by the blood. It is removed 
from the body by all the excretions, as the expired air, the 
evaporation of the sweat, the urine, and also by simple 
conduction into the air about. 

Regulation of the body temperature. By a certain regu- 
lation of the mechanism of the body, the production and 
elimination of heat are always equalized, so that the tem- 
perature of the body remains constant. This is 98.6o F., 
taken in the mouth. When more heat is produced, as 
by active exercise, the peripheral circulation and the per- 
spiration are increased, and thus more heat is removed 
from the body by conduction and evaporation. When the 
surrounding air is very hot the production of heat in the 
body is lessened and the perspiration and evaporation are 
very profuse, so that the bodj^ does not get any hotter. 
When the air is cold the production of heat is increased and 
the peripheral vessels are contracted, so that less heat goes 
to the surface and thus less is conducted away, and the 
internal organs of the body become no colder. 

Sources of body heat. The heat energy comes from the 
tissues, and these from the food ; so that in an indirect 
way the heat is produced from the food. When more work 
is done, more energy is needed and more liberated ; so more 
tissue is burned, and therefore more food must be taken to 
keep up the equilibrium. If we burn a food outside the body 
and estimate its energy in heat, we find that this is the same 
as the energy which the food produces in the body in heat 
plus work, provided always the food can be digested and has 



WASTE AND EXCRETION 211 

no poisonous action. Certain foods, as the fats, have great 
heat-producing energy stored up, and where such energy is 
required, as in cold weather, such foods are very useful. 

A comparison of the effect upon the body heat of the 
consumption of a given amount of a regular food substance, 
as fat or carbohydrate, and of the same amount of alcohol, 
is interesting, as it ilhistrates the difference in the action of 
a food and a poison upon an important body function. 

Fat, alcohol, and sugar are all hydrocarbons. When they 
are burned or oxidized outside of the body they give rise to 
a certain amount of heat. Fat causes most heat, alcohol 
next, and sugar least. It might be argued, therefore, that 
the body could get heat from them in this order. When, 
however, we feed a person upon each of these substances 
and allow them to burn in the body, we find that alcohol 
causes a loss of body heat, so that the body is colder, not 
warmer, while fat or sugar causes it to keep up its normal 
heato The alcohol contains more heat, as we have seen, 
than the carbohydrate; but its poisonous action upon the 
system is such that the body fails to get the benefit of the 
heat which is in it. 

Eflfect of alcohol on body temperature. This maintenance 
of the body heat is necessary for the health of the body. 
It fortifies us against cold. So that, if we were going out 
into the cold, the worst thing which we could do would be 
to take any alcoholic liquor, for we should be throwing 
away some of the heat which the body would need to resist 
the cold. Many people do not know this. Tliey think that 
because the alcohol makes them feel warm the body is. 
therefore warmer. But travelers in frigid climates have 
learned the fallacy of this idea by hard experience. 

This action of alcohol in reducing the body heat and the 
power of resistance against cold is well illustrated by an 
adventure which is recorded of several travelers who were 



212 PHYSIOLOGY AND HYGIENE 

canglit in a snowstorm in the Sierra Nevada Mountains. 
These travelers lay down to sleep exposed to very great 
cold. Several took a large amount of alcohol. It made 
them feel warm and comfortable, and they fell asleep. 
Others took a little alcohol. Others took none, but went to 
sleep feeling chilly. In the morning the men who took 
much alcohol were frozen to death ; those who took a little 
were frost-bitten ; and those who took no alcohol suffered 
no serious results from the exposure. 

Alcohol dilates the peripheral vessels, and more blood gets 
to the body surface. Now, in cold weather we need all our 
heat inside to keep the vital organs w^arm. If we take 
alcohol the l)lood carries the heat to the skin, and it passes 
into the cold air. It makes us feel warm, because we feel 
the hot blood in the skin ; but it uses up our heat, and we 
suffer for it. The travelers who took no alcohol felt chilly, 
but they kept their hearts warm at the expense of their 
skin and w^ere all right. Those who drank warmed the 
surface of the body tit the expense of the heart and lungs. 

DEMONSTRATIONS AND EXPERIMENTS 

1 . Run the point of a needle which has been passed through a flame 
(to sterilize it) beneath the outer layer of skin upon the hand. Note that 
this ''skin" can be separated from the layer beneath. No bleeding 
results from puncture of this layer. Why? 

2. Wash the hands in warm water. Dry them and rub them 
together with force. The fine powder of scales which appears upon 
the surface is part of the outer horny layer of skin. 

3. Obtain a sheep's kidney. 
Strip the capsule. 

Find the vessels which go to and from the kidney. 

Note the difference in the appearance of the peripheral layer 
(cortex) and the inner substance. 

Can you distinguish the pyramids? 

The glomeruli and tubules can be made out in sections prepared for 
microscopic examination. 



WASTE AND EXCRETION 213 



QUESTIONS 

I. When coal is burned in a furnace, what are the products? What 
happens if the ashes are not taken away? What are the products and 
ashes which are formed by the combustion in the body cells? What 
would happen if these were not taken away? What are the organs 
called whose function is to rid the body of these waste products? How 
does the waste get from the cells to the blood ? From the cells to the 
excretory organs? 

II. What waste products are excreted by the lungs? How does the 
composition of the blood that comes away from an active muscle differ 
from that which enters it? What waste products are excreted by the 
kidneys? Describe the kidneys. What is a glomerulus? A tubule? 
What is the difference between the blood which flows into a glomerulus 
and that which flow^s out of it? Where does the water which it loses go? 
Describe the composition of the waste substances which are taken from 
the blood or built up from the blood by the kidneys. 

HI. What is urea? What are the ureters? What waste substances are 
excreted by the skin? Describe the skin. What other functions has it 
besides excretion? Describe the hair. What is its use? What are the 
sebaceous glands? What are the principal excretory structures of the 
skin ? 

IV. Describe a sweat gland. Of what does perspiration consist? What 
else besides perspiration is eliminated by the skin? What is insensible 
perspiration? What is the effect of the moisture in the air upon the 
elimination of heat on a hot day? On a cold day? What are the nails? 
Of what use are they? What becomes of the undigested part of the 
food? 

V. Why must we keep up an active circulation ? What practices serve 
to accelerate excretion by the skin? What is tlie proper clothing in 
winter? In summer? What is the effect of a daily bath? Why should 
we be regular in the operation of the bowels ? 

VI. How is the body heat produced? How is the temperature of the 
body regulated? Why does not the blood get much hotter upon a warm 
day than upon a cold one? What foods are great heat producers? 
What is the effect of the drinking of alcoholic liquors upon the main- 
tenance of body heat? Does warm clothing economize food? Why do 
we need more covering while asleep than during the day? 



CHAPTER XI 

THE NERVOUS SYSTEM 

THE special activity of all the organs of the body (the vol- 
untary and involuntary actions which together make up 
the total activity of the organism) is controlled and regulated 
by a system of organs known as the nervous system. Through 
this control each motion of the muscles is regulated, and the 
secretion of a gland and the constriction of a blood vessel 
accomplished. Through the medium of this system all the 
organs work together for the common good. 

When we desire an object tliat we see, as an apple, the 
idea of obtaining it is aroused in the mind. This thought 
of getting the apple sets in motion the nuichinery for ob- 
taining it. Messages from the brain go to the leg muscles, 
and we walk toward it. Then messages go to tlie hands, 
and we reach out and take it ; a message from the eyes goes 
to the brain, telling us wliei'e to grasp. We put it to the 
mouth. Then from the brain messages go to the jaws and 
tongue, and we eat and swallow the apple. So far all these 
acts, with the exception of a part of the act of swallowing, 
have been voluntary. The nervous system has been direct- 
ing our motions, but we have had to think about the process, 
and could have stopped it at any time. After the apple is 
swallowed, a message from the stomach goes to the nerve 
centers, and the machinery for secretion of juice to digest 

214 



THE NERVOUS SYSTEM 216 

it is set in action. Then the digested apple is absorbed and 
carried to the cells by the circnUxtion, the machinery of which 
is always going. 

The action of secretion is an involnntary action. It is 
regnlated by the nervous system, just as is walking, but it 
is done without our consciousness. So with the circulation 
of the blood. 

Thus the whole process of taking in food and using it is 
under direction of the nervous system. If the connection 
between this system and the muscles is cut off, these muscles 
cannot act. We may desire the apple, but we cannot get it. 
If the connection with the stomach is cut off, the stomach 
will be there and the food will be there just the same as 
before, but no secretion will occur, and the food will not be 
digested. 

The nervons system not only regulates each separate act, 
but by its connections and mental processes enables all the 
various functions, sight, movement, secretion, to work to- 
gether for a common end. 

I. THE ORGANS OF THE NERVOUS SYSTEM 

The nervous system is made up of the brain, the spinal 
cord, and the nerves. 

Speaking in a general way, the nerves carry impulses to 
the organs from the brain and cord, and from the organs 
back again. The brain and cord receive impulses by the 
nerves and send out impulses by them. They are the cen- 
tral office where all the reports are received, records kept, 
and directions issued. Thus, if the sole of the foot itches, 
this message goes to the central system. It is recorded 
here that scratching stops this itching, so the machinery 
for scratching the sole is set going and the itching 
relieved. 

HEWES, P. .to H.~U 



216 



PHYSIOLOGY AND HYGIENE 



The Irain lies in tlie bony sknll. Continuons with the 
brain, the spinal cord extends downward from the foramen 

magnum of the sknll, in the spinal 
canal of the vertebral colnmn, to 
the base of the spine. 

To and from the brain and cord 
rnn the nerves. They are distrib- 
uted throughout the organs and 
structures of the body, connecting 
these with the central nervous sys- 
tem, the brain and cord. 

The central system consists of 
nerve cells, and nerve fibers con- 
necting these cells with one another 
and with the nerves. The nerves 
consist of nerve fibers continuous 
witli the fibers of the brain and cord. 

The nerves. The nerves of the 
body are of two kinds. One set 
carries sensations from the skin 
and organs to the central system. 
These are called afferent (Latin ad, 
"toward," iuidfero, "I bear ") nerves. 
Others carry impulses from the cen- 
ters to the parts. These are efferent 
(Latin ex, ''from," and /^ro," I bear") 
nerves. The afferent nerves arise 
in the organs of sense, as the eye, 
the taste papillae of the tongue, the 
skin, and carry sensations from 
these inward. They are sensory 
nerves. The efferent nerves arise 
in the nerve cells of the brain and 
cord, and carry impulses outward. 




Brain and cord, showin 
nerves cut close to cord. 



THE NERVOUS SYSTEM 



217 



The structure of both sets of nerves is the 
same. Most nerves consist of bundles of fine 
fibers hehl together by connective tissue. 
Each fiber consists of a central column or 
strand of soft protoplasmic substance, called 
the axis cjjUnder. This is inclosed in a 
sheath known as the medullary {medulla, the 
substance of the central canal of bone) sheath. 
Outside of this is another sheath, the neuri- 
lemma (Greek neuron, ''nerve," and lemma, 
"husk")- The central axis cylinder and the 
outer neurilemma sheath are continuous 
throughout the nerve. The medullary sheath 
is broken at regular intervals. These breaks 
are called nodes. In the parts of the nerve 
between the nodes a nucleus may be found 
just beneath the sheath. The fibers have a 
white appearance and are called medtdlated 
nerve fibers. 

In some nerves there is but one sheath, the 
neurilemma. These are called nonmedullated 
fibers. 

Nerve ganglia. In the course of some nerves 
occurs a slight enlargement called a ganglio7i. 
A ganglion is made up of cells mixed with 
fibers. These ganglion (Greek gagglion, ''a 
knot") cells are nerve cells. They are large 
cells with a nucleus and an irregular outline. 
Each cell has many branching processes. One 
process of each cell is continuous with the 
axis cylinder of a nerve. 

The cord. The spinal cord is a column of 
white appearance, lying in the spinal canal 
of the vertebral column. It is continuous at 



Axis cylinder 
at node 



Medullary 
sheath 



Outer sheath— > 




A nerve fiber. 



218 



PHYSIOLOGY AND HYGIENE 




Section of spinal cord, Math nerves. 
a, ganglion in root ; s, sensory root ; m, motor root. 



the top witli the brain. At the base it tapers to a fine fila- 
ment. Its length is about eighteen inches, its width half an 
inch. Its shape is cyhndrical. 

Along the front runs a deep furrow, the anterior fissure. 
At the back is a similar furrow, the posterior fissure. Be- 
tween these fissures is an isthmus of cord substance con- 
necting the right and 
m 



left halves of the 
cord. In these fis- 
sures runs connec- 
tive tissue carrying 
blood vessels. 

In cross section the 
cord is seen to con- 
sist of a superficial layer of wdiite substance aud a central 
zone of gra}^ substance arranged in the forin of an H, each 
bar of the H being a crescent with two horns. 

The white matter consists of nerve fibers, most of which 
run lengthwise in the cord. 

The gray matter consists of cells, among which many 
white nerve fibeis and gray nonmedullated fibers run in all 
directions. The cells are nerve cells, resembling those de- 
scribed as ganglion cells. 

The spinal nerves. From the spinal coi-d thirty-one pairs 
of spinal nerves are given off at intervals along the cord. 
These nerves emerge through the intervertebral foramina be- 
tween the vertebral arches. Each nerve has two roots— an 
anterior root w^hich enters the anterior region of the cord, 
and a ijosterior which enters the posterior part of the cord. 
Upon the posterior root is an enlargement known as a 
ganglion. The two roots unite in the bony foramen to 
form the nerve, which proceeds to the muscles or skin or 
some organ. 

In the anterior root the white fibers of the nerve run to 



THE NERVOUS SYSTEM 



219 



the anterior horn of the gray matter of the cord. Here a 
fiber unites with a cell of the gray matter. As described in 
connection with gangli- 
on cells, one fiber from 
a nerve cell becomes 
the axis cylinder of a 
nerve fiber. The ante- 
rior root carries the sen- 
sory nerve fibers of the 
spinal nerve. 

In the posterior root 
the fibers take their origin 
from the cells of the gan- 
glion on the root. These 
ganglion cells are con- 
nected again with the cells 
of the posterior horn of 
the cord, bnt by fibers of 
the nonmedullated kind. 
The posterior roots carry 
the motor nerve fibers, 
which take messages from 
the cord to the parts. If 
this root is cut there will 
be feeling in the part sup- 
phed by this nerve, but no 
power to move. Each spi- 
nal nerve, then, consists of 
a nerve trunk carrying both 
sensory and motor, afferent 
and efferent nerve fibers, 
which decussate, or cross, at the cord, the sensory fibers 
entering the cord by the anterior root, the motor by the 
posterior root. 




Nerve cell. 
a, axis cylinder. 



220 



PHYSIOLOGY AND HYGIENE 



The cord is thus made up of nerve ceUs connecting with 
the fibers of the nerves, and also of fibers connecting these 
same cells with the cells of the brain above. 

The brain. The brain lies in the skull. It consists of 
several parts. The low^er part, attached to the cord, is called 
the medulla oblongata. Attached to the medulla and lying 




The brain. 



mostly behind it is the cereheUiim (Latin, "little brain"). 
The two lateral parts of the cerebellum are connected by 
a fibrous bundle running in front of the medulla, the pons. 
Above the pons the bundles of nerve fibers of the medulla 
are collected into two pillars, the crura (Latin crus,^'leg^' — 
legs of brain) rerehri. These pillars diverge and run up- 
ward to the cerebrum (Latin, "brain"), one to each hemi- 
sphere. 

The cerebrum makes up the larger part of the brain. It 
consists of two hemispheres connected by a band of fibers, 



THE NERVOUS SYSTEM 



221 



the coi'jms (Latin, ''body") callosum. The surface of the 
hemispheres is furrowed by convolutions (Latin con., "to- 
gether/' and volvere, " to roll ") separated by fissures (Latin 
findere, "to split")- Be- 
tween the two hemispheres 
is a deep median fissure. 
The surface of the brain 
is gray, being composed of 
gray matter. The deeper 
parts of the brain are 
white, consisting of fibers 
running from the cells of 
the gray substance into 
the crura and cord below. 

The outer gray part, or 
cortex (Latin, "bark"), of 
the cerebrum consists of 
many nerve cells con- 
nected by many nonmed- 
ullated nerve fibers. 

The deeper white part consists mostly of white medul- 
lated nerve fibers, each with an axis cylinder starting from 
a nerve cell in the cortex. 

The lower parts of the brain, the crura and medulla, con- 
sist, like the cord, of mixtures of these gray and white sub- 
stances. The white fibers run from the cerebrum through 
the crura and medulla, to become fibers of cranial nerves or 
to join cells of the cord, which are the origin of spinal 
nerves. Both the fibers which leave the brain, the motor, 
and those which come to it, the sensory, cross to the other 
side of the body from that on which they started before 
reaching the organ or nerve cells to which they go. This 
is called the decussation (Latin decussare, "to divide cross- 
wise") of the nerves. Consequently an injury to the right 




Upper surface of cerebrum, showing 
convolutions and fissures. 



222 PHYSIOLOGY AND HYGIENE 

side of the brain causes a paralysis of the left side of the 
body. 

The cranial nerves. Twelve pairs of nerves arise from 
the brain, each nerve snpplying a corresponding part of the 
body on the right or left. 

The first pair are called the olfadonj (Latin olfacere, " to 
smell") nerves. They arise from the olfactory bnlbs on the 
under side of the cerebral hemispheres and run to the nose. 
They are the nerves of the sense of smell. 











Section of brain ; cells and fibers. 

The second pair are the nerves of sight. They arise from 
the region of the crura and run to the eyeballs. 

The third smd fourth pairs supply the eye muscles. Tliey 
are motor. 

The fifth pail' arise by a motor and sensory root like 
the spinal nerves.- Each nerve divides to three principal 



THE NERVOUS SYSTEM 223 

branches. It supplies motion to the face and jaw, and is a 
sensory nerve of part of the face, eyelid, and tongue. 

The sixfh pair sup^^ly one muscle for each eye. 

The last six pairs arise from the medulla. 

The seventh supply the muscles of the face and scalp. 

The eighth are the nerves of hearing-, running to the ears. 

The ninth sup])ly the })liarynx with motion, and are tlie 
sensory nerves of taste. 

The tenth supply the larynx, the muscles of respiration, 
and the heart, stomach, intestines, and liver. They are called 
the pnemnogastnc (Greek imeunwn, "lung," and gaste); 
"stomach '') )ie)-i'es, from their important connection with the 
lungs and stomach ; also the ragus, or wandering nerves, 
because they go to so many organs. 

The eleventh supply the muscles of the neck. 

The twelfth supi)ly the muscles of the tongue. 

The meninges. The brain and cord are surrounded by 
protecting membranes. Closely adherent to the brain and 
carrying the blood vessels is a delicate membrane, the pia 
n}((ter (hditiw, "tender mother"). Outside, close to the skull 
wall, is a firm membrane, the dura mater (Latin, "hard 
mother"). A thin layer of cells lining the pia, and another 
layer lining the dura, together make the third membrane, 
the arachnoid (G-reek arachne, "a spider's web," and eidos, 
"resemblance"). In the space between the two layers of 
the arachnoid is a liquid, the cerehro-sjnnal flnid. 

Inside the brain and cord is a continuous canal which 
contains fluid. In the brain this canal expands to several 
large spaces called ventricles. 

The sympathetic (Greek sun, "together," and pathos, "feel- 
ing") nervous system. In addition to this main nervous 
system of brain, cord, and nerves, there is a second nervous 
system appended to it, the sympathetic system. This is 
made up of a series of nerve ganglia which lie along the 



224 PHYSIOLOGY AND HYGIENE 

outside of the vertebral column from skull to coccyx. Each 
ganglion is connected to the ganglia above and below, thus 
forming a chain. Branches from many spinal nerves and 
some of the cranial nerves connect this system with the 
central system. From this chain nerves pass to the viscera 
of the abdomen and thorax. It is principally the nerves 
from this system which control the muscular action in the 
blood vessels. 

The fibers of many of these nerves of the sympathetic 
system are nonmedullated. 

II. THE FITNCTIONS OF THE BRAIN AND THE SPINAL CORD 

Psychical (Greek psuclie, ^'mind'') centers. The cerebral 
liemisplieres are the seat of sensation, volition, and in- 
telligence. 

Any contact with the outer world, as a toucli, a taste, a 
sound, a pin prick, or a blow, is perceived here. If the 
brain is benumbed, touch or even pain is not felt. A 
man whose brain is benumbed by the administration of 
ether does not know that the dentist is pulling his tooth, or 
feel any pain when it is pulled. 

All voluntary acts originate here. The cells from which 
voluntary movements of the hand originate are situated in 
a certain part of the hemispheres. If this region of the 
brain is injured the hand cannot be moved, however hard 
the man may try to move it. 

All consideration of the meaning of things is here. A 
man whose brain is stupefied by alcohol does not know the 
difference between a hat and an umbrella. He does not 
understand what is said to him. 

Reflex (Latin re, '^back," and flectere, ''to bend") centers. 
The spinal bulb or medulla and the cord are the seat of many 
of the processes of life which we call mitomatic and reflex 



THE NERVOUS SYSTEM 225 

acts (Experiments 1 and 2, p. 233). The act of breathing is an 
instance of an automatic action. This process goes on with- 
out our consciousness or will. We can stop it for a short 
time, or change its rate by the act of the higher brain, but as 
a rule it is regulated from the medulla. It goes on in frogs 
after the cerebrum has been removed. There are many in- 
stances of reflex action, as the drawing tip of the foot when 
the sole is tickled, the working of the eyelid at a bright 
light. The person does not stop to think before acting in 
these cases. The parts act for themselves. These reflex 
acts can be controlled by the will, as we need not draw np 
the foot if we previously determine not to. There are fibers 
which run from the cerebrum to these centers. If we send 
a current from the brain through these, we stop the act; 
but as a rule the act goes on without interference. There 
are some actions with which the conscious will cannot nor- 
mally interfere, as, for instance, the beating of the heart or 
the secretion of the intestine. They are purely automatic, 
but they are regulated by the nervous system. The secretion 
of the intestine is a reflex act. This is not going on con- 
tinuously. When food reaches the intestine a message goes 
to the reflex center, the machinery of secretion is set in 
motion by a counter message from the nerve center, the 
secretion of the pancreas begins to flow, the bile which has 
been stored in the gall bladder begins to pour into the 
intestine, and digestion is accomplished. Most of the pro- 
cesses essential for existence are of this nature. They do 
not require the attention of the psychical centers, the mind. 
Metabolism in the brain. Whenever we think or act, per- 
ceive an odor or hear a sound, some change takes place in 
a cell of the nerve tissue in the brain or cord. There is 
a combustion of tissue here, just as in the muscle cells 
when those organs contract. The brain cells are wasting 
and building all the time, just as are the cells elsewhere. 



226 PHYSIOLOGY AND HYGIENE 

Localization. Tlie different functions of tlie body have 
their own center in a special area of the brain. Tims, the 
function of speech is in one place, that of writing in another ; 
the movements of the hand have their centers in one part, 
those of the foot in another. Sometimes we have an injury 
or disease of the brain which affects a small part, perhaps 
one of these special centers only, and then the mail can pei*- 
form every function as before, except the function whose 
centc is affected. Thas, he may be able to think, walk, 
talk, but not move his right hand: He may know what he 
wishes to say, but not be able to say it, if his speech center 
is affected. 

Hygiene of the nervous system. The nervous system, like 
the muscular sj'stem and the skeleton, is developed by use. 
Just as the muscles are made stronger by running and row- 
ing, the brain is made stronger and more efficient by study 
and thought and action; and, like the other organs of the 
body, the brain, if it is not exercised and cared for, will be 
less developed and less useful than it should be. 

The soundness and training of the nervous system are of 
first importance, since all the functions and actions of the 
body and its organs are regulated by it. A body with a 
weak or untrained brain is like an army with an incompetent 
general. However strong a man's muscles may be, unless 
he has a sound nervous system to control them, he cannot 
do good work or endure sustained exercise with them. Un- 
less he has a brain which has been trained by thought and 
experience, he cannot properly direct his work, and much of 
his strength will be wasted. Thus, a trained carpenter can 
build a house twice as quickly and twice as well as a much 
stronger man who has not learned the trade. 

A man may sustain the health or soundness of his nervous 
organs by taking plenty of food to nourisli them, plenty of 
sleep to rest them, by exercising them in thought and action, 



THE NERVOUS SYSTEM 227 

and by avoiding all practices which iujure them, as over- 
work or indulgence in alcohol and other substances which 
poison them. 

Education. The training or exercise of the nervous system 
is the business of education (Latin ex^ "out," and ducere, "to 
lead''— to lead forth). 

Nature's method of training or education consists in the 
formation of habits (Latin habere, " to have "). Thus, the child 
learns to walk, to talk, and to swim by imitation of others. 
At the start the processes take some thought and many trials 
for their accomplishment, but when learned the}^ are accom- 
plished automatically, without any conscious thought as to 
the process. They become habits. In the same way the 
child acquires the habits of obedience and of conscience. He 
grows up to obey his parents without reasoning why in each 
instance. He feels that he must not do anything which he 
knows to be wrong, must not tell a lie to avoid punishment. 
This is his conscience habit, which keeps him upright with- 
out his reasoning about it. 

In the further education of the child or man, we adopt and 
utilize this same method of nature, the formation of habits. 

Object of training. Thus, in learning to write, the child 
studies the formation of each letter in repeatedly copying 
the letters and putting them together. Finally he writes 
them offhand without thinking about their formation and 
mthout a copy. The wood carver or the weaver becomes 
so expert that the fingers work almost without thought. 

At first we think much about the right way to do a thing. 
We study each step carefully, and then we dp it frequently. 
Finally we do not think of the steps at all; we wish to do 
it, and the thing is done almost without thought. 

As the result of such education the child or man becomes 
so accustomed to these right habits of doing and thinking 
that he becomes confirmed in good habits and well doing. 



228 PHYSIOLOGY AND HYGIENE 

Object of study. The mind is trained by the study of 
mathematics, language, physics, philosophy, to develop its 
powers of reasoning and thinking. It is not so much the 
fa(;ts which the child learns as the habits of quick and 
accurate thinking which count. With these habits he is in a 
position to make the most of the knowledge and experience 
which he acquires later. If he has gained the habits of ac- 
curate observation and of perseverance and industry, he is 
well equipped for his progress through the world. 

Education is b}^ no means confined to the schools. The 
greater part of it is obtained in the home and in the com- 
munity about us. At home the boy is given good books, 
that he may read of the good deeds and noble lives of the 
world's history. He is taught courtesy and charity, that he 
may make those about him happier. He is taken to walk 
in the woods and fields, and instructed in the story of the 
rocks and plants and animals, that he may come to love na- 
ture and to find an interest in studying its works. He is 
taken to see great works of art and to hear good music, 
and taught to care for poetry, that he may acquire refined 
tastes and see more of the grace and beauty in life. 

In this education it is not enough that children shall 
read books or see paintings or sculptures. They must be 
taught to appreciate the meaning which is in the work, to 
feel the spirit which inspired the writer or painter who 
conceived it, and to understand the thoughts and ambitions 
and passions which have molded the lives of the men and 
women who have made the history of which they read. If 
they learn these things, to them life becomes filled with an 
interest and a joy which can never die. 

" He ate and drank the precious words, 
His spirit grew robust, 
He knew Ji6 more that he was poor 
Or that his frame was dust ; 



THE NERVOUS SYSTEM 229 

He danced along the dingy days — 

And that bequest of wings 
Was but a book. What liberty 

A loosened spirit brings ! " 

A most important habit to acquire is that of self-control. 
It is this quality perhaps beyond all others which distin- 
guishes manhood. The emotions of sympathy, love, pity, 
enthusiasm, religion, are all excellent elements of our char- 
acters. They help to ennoble us and to lead us to strong 
endeavor, high thought, and worthy action. But they lose 
much of their usefulness if they are not controlled by judg- 
ment and a sense of justice and right, so that they are 
allowed to sway us only for the greater good of those about 
us. More especially should the passions of anger, jealousy, 
sensuality, and the many ignoble impulses which arise from 
the desire of possession be controlled.^ In the submission 
to these lies a great part of the woe and crime which darken 
the pages of history. 

True happiness comes not through the gratification of the 
desires for the material things of the world about us, but 
from the possession of a well-balanced mind which can dis- 
cern the real treasures of life, and a spirit inspired with the 
pursuit of truth. 

Everybody has affinities for truth and cultui-e. If they 
are developed the man will take his pleasure in good pur- 
suits ; if not, he will indulge in sensual pleasures. Every- 
body should be athletic, but he should also be clever and 

1 There is pliysiologica,! necessity for con-eet emotional conditions of the mind. 
Professor Gates of the United States Commission of Biological Research has shown by 
chemical tests that the human tissues and fluids are affected by emotions. "He has 
found that the blood of a large number of people after an attack of ill temper responds 
uniformly to a certain chemical test ; the blood of a large number after attacks of jeal- 
ousy responds to another chemical test; of others, after gi"ief, to another; and so on 
through the line of emotional conditions. And never has it failed that the chemical 
generated by any malevolent, inharmonious mental condition is of an acid, acrid, poi- 
sonous nature. " — Maria L. Pratt, M.D., of Durant Gymnasium, in Report of National 
Educational Association, 1896, p. 931. 



230 PHYSIOLOGY AND HYGIENE 

refined. In these days a clever head and a well-trained 
mind will accomplish far more than mnscular strength. 

One-sided development. Care mnst be observed in this 
training not to become developed entirely in one direction. 
We see too many men whose brains are admirably developed 
for bnsiness, bnt who have no interest in art or literatnre. 
Too many, on the other hand, are so engrossed in the pnrsnit 
of one kind of knowledge that they are ignorant of the 
truth wliich underlies development in the more practical and 
essential aptitudes of human nature. 

Sleep. In exercise of the nervous system we must be 
careful not to overwork. We must be sure to get 
enough sleep. The muscles rest between periods of exer- 
cise, the stomach rests between meals, but the nervous sys- 
tem is always active during waking hours. Whenever we 
think or move or see or feel the nervous system is in action. 
Therefore it gets complete rest only in sleep. Even here 
parts of it are active, but the most of it rests. Every 
one should allow eight hours for sleep, and the sleep 
should be taken at a regular time, as nature likes regularity. 
W^e sleep best at night, as the darkness is favorable to the 
condition. 

It is reasonable to suppose that the cells of the brain and 
nerve tissue become depleted after labor and need a period 
of rest in which to rebuild their substance. Careful histo- 
logical investigations show that this svipposition is a true one. 
Changes in the character and contents of the cells can be 
observed during the working or resting stages.^ 

The danger of overworking the brain or the body is espe- 

1 Professor C. F. Hodge of Clark University, with other physiologists, has conducted 
numerons experiments relating to the subject, which are full of interest. One of the 
results reached has been the observation that after a severe effort a rest of twelve 
hours is required to enable the cell to return to its normal condition ; that often even 
twenty-four hours is scarcely sufiScient for this purpose. It thus appears that there is 
physiological basis for a periodical rest day in which the worn-out cells may be able to 
recover their store of energy. — Dietetic and Hygienic Gazette, August, 1898, p. 518. 



THE NERVOUS SYSTEM 231 

cially great in these days of the telephone, the telegraph, and 
express trains. A business man to-day can transact many 
times as much business in twenty-four hours as his grand- 
father could in a week. To do this, however, he has to use 
his mental faculties to the utmost. Every one, especially 
brain workers, should make a point of taking a good va- 
cation twice 3^early. 

One of the best means of rest is a change of occupation. 
To rest the brain it is not necessary to vegetate. It is 
simply necessar}'- to take the interest off one set of ideas 
and place it upon another. A man gets more rest in read- 
ing a good book or in seeing a good entertainment after a 
hard day's work than if he sat about doing nothing. Travel, 
or sojourn in the country where he can ride and climb, play 
golf or ball or cricket, will do a business man far more good 
than sitting about the piazzas of summer hotels at fashion- 
able watering places. 

In connection with this subject the custom observed in 
Christian countries of suspending all business every seventh 
day is a most beneficial one, one which doubtless adds ma- 
terially to the health and longevity of the people. 

Alcohol. The nervous system is very susceptible to the 
influence of alcohol. Much of the harm which this substance 
does is accomplished through its influence here. 

The first effect of the drinking of alcoholic liquors upon 
the nervous system is to cause a sense of exhilaration. The 
man feels lively and like making effort. Now, this very first 
effect of alcohol is a bad one, for the sense of exhilaration 
and power is a false sign. The man thinks that he can do 
more work, but in reality he can do less. His sense of 
fatigue is paralyzed, so that he does not know w^hen the 
muscle centers have exhausted themselves.^ Thus he goes 

1 The view of Schmiedeberg that the action of alcoliol upon the nerve centers is 
always a paralyzing one is now accepted by most physiologists. 
HEWES. P. & H.— 15 



232 PHYSIOLOGY AND HYGIENE 

on working at the expense of liis health. In this way one 
of nature's safeguards against overwork is broken down by 
the creation of this false sense of exhilaration. The heart 
and other organs work more rapidly for a time and wear 
themselves out the sooner. 

In the second place, this sense of exhilaration which people 
get from alcohol is followed by a sense of relaxation and 
inertia. When the effect of the alcohol is gone, the man 
feels less able to work than before. To get rid of this feel- 
ing of laziness and distraction he frequently takes more 
liquor. After a time small amounts of liquor cease to 
relieve the relaxation. 

Alcohol habit. The man begins to take larger amounts, 
and thus what is known as the alcohol habit is formed. The 
man has so relaxed his system by the use of alcohol, and 
has become so dependent upon it for the feeling of energy 
which he desires, that he thinks he 'jannot get along without it. 

Now he finds that the constant or large doses which he 
takes are injuring his health and capacity to work. His 
heart is less able to stand exertion, his mind is less clear. 
He determines to stop the use of liquor, or reduce it. But 
now he finds that he cannot. The alcohol appetite has so 
grown upon him that he cannot resist it. His will has been 
weakened by the indulgence, and cannot defend him against 
his enemy. Thus he may go on until his health is gone and 
his business affairs are ruined through incapacity and neglect. 

Such a career as the above is no uncommon one. Many 
men who begin by drinking beer or wine or cider in what is 
called moderation acquire tlie alcohol habit. It is this 
power of alcohol upon the nervous system to establish a 
"habit" which is one of its most dangerous qualities, and 
which makes it a thing to be avoided. No man knows, when 
he takes his first glass, whether it may not be his fate to 
become a victim of this habit. 



THE NERVOUS SYSTEM 233 

DEMONSTRATIONS 

1. Cross one knee over the other, and let the leg hang loosely. 
Strike the upper leg sharply with the hand just below the kneecap. 
The lower leg will jerk suddenly forward. This is an example of a 
muscular movement occurring without the intervention of any thought 
upon the part of the individual. 

2. Tickle the nose with a feather. The sneeze which follows is a 
reflex act of the body to rid itself of the source of irritation to the 
mucous membrane of the nose. 

3. Pass the hand rapidly close to the eyes of the pupil next you. 
The rapid winking of the lids is an example of an involuntary action 
established to protect the eye. 

4. Note the deep and rapid respiration which replaces the ordinary 
respiration after exertion, as running. This is an automatic action in 
response to the need of more respiratory exchange to supply the in- 
creased combustion resultine: from the increased muscular action. 



QUESTIONS 

I. How are all the vital processes of the body, the digestion, circula- 
tion, and so forth, regulated so that they all go on together in time and 
place for the common good? In what part of the body must there first 
be an action that a muscle may contract, or that an arm or leg may be 
moved? What are the organs of the nervous system? What is the func- 
tion of each part of this system? Of the nerves? The cord? The brain? 
How are nerves classified according to their functions? Describe a 
nerve. What is a nerve ganglion? 

II. Describe the spinal cord. How many nerves join the cord? 
What two sets of fibers does each spinal nerve carry? Where is the 
brain situated? Describe the brain. In which side of the brain are 
located the cells which regulate the action of the right side of the body? 

III. Name some of the cranial nerves. What are the meninges? Is 
the nei've of sight motor or sensory? Is the nerve of hearing motor or 
sensory? Is the pneumogastric nerve motor or sensory? Classify the 
spinal nerves as motor or sensory. 

IV. What is the sympathetic nervous system? What is the function 
of the cerebral hemispheres? What kind of acts originate here? Can. 



234 PHYSIOLOGY AND HYGIENE 

the muscles act if the nerve which connects them with the brain or cord 
is cut? What kind of acts take place without the use or intervention 
of the brain? Describe a reflex act. Name some of our actions which 
are done without our thinking. What occurs in the brain cells when- 
ever we think or perform a voluntary action? 

V. Can the brain and nerve system be developed? How? What is 
the training of the nervous system called? What are habits? What is 
the chief end of the study of mathematics and grammar? Why should 
we read good books? When does the nervous system rest? Wliy is the 
nervous system susceptible to the action of alcohol? What is the most 
dangerous feature in regard to the action of alcohol upon the nervous 
system? Can a man tell when he is forming the alcohol habit? 



CHAPTER XII 

TOBACCO - OPIUM- COCAINE 

BESIDES alcohol there are other substances used by 
men against the use of which, on account of their 
harmfulness to health and development, every one should 
be warned. Such substances are tobacco, opium, cocaine, 
Tobacco. Among- these substances the one most com- 
monly used in this part of the world is tobacco. It contains 
a very poisonous substance known as nicotine. The smoke 
of tobacco contains several irritant substances formed from 
the combustion of the tobacco fiber and the nicotine. When 
this smoke comes in contact with the mucous membranes of 
the mouth and upper air passages it has an irritant action 
upon them. In constant smokers this irritation results in a 
relaxation of the structures of the membrane, Tvnth changes in 
the cells and the secretions. These changes frequently end 
in a condition of chronic pharyngitis. If you look at the 
throat of habitual smokers you will often see pearly patches 
on the membrane, showing areas of chronic inflammation. 
The, throat will have a red, beefy appearance, instead of the 
moist, pink appearance of the normal throat. This chronic 
condition of the membrane makes the throat susceptible to 
exposure to cold and disease infection, so that the smoker 
is less able to resist the diseases of the mouth and throat 
than the abstainer. 

235 



236 PHYSIOLOGY AND HYGIENE 

This condition of irritation of the mucons membranes is 
very detrimental, but it is not the most serious effect of 
tobacco smoking. The pyridine and other substances which 
are taken in with the smoke, and the nicotine which is 
sucked in from the tobacco, are absorbed into the system, 
where the\^ act as poisons. These substances ap])ear to 
poison the red corpuscles of the blood, destroying their 
hemoglobin and diminishing their oxygen-carrying capacity. 
Lack of oxygen in the tissues follows, and tlnis develo})- 
ment of the organs and the body is hindered. Y^ou will 
often notice the pallor and stunted development of youths 
w4io are habitual smokers. The skin has a sallow, unhealthy 
look. This is particularly true of those who smoke in boy- 
hood, before their development has been completed. The 
growing tissues are especially susceptible to the influence of 
poisons. Any boy who smokes before the age of twenty-one 
runs the risk of growing up with stunted development, with 
weak muscles, a poor braiu and nervous system, a weak 
heart, and no power of endurance. 

The poison of tobacco has a marked effect upon the heart. 
The action of the heart is much weakened ; its beat becomes 
irregular and rapid with any exertion. Many a boy or 
man who has smoked without any thought of harm from 
it finds, when he comes to be examined for admission to 
some athletic contest or to the army, that he is debarred 
owing to the fact that he has a ''tobacco heart." 

Smoking has a bad effect upon the nervous system. The 
effect may appear to be sootliing or even stimulating for 
the time, but it ends by making the person irritable. 
Through its poisonous effect upon the nervous system, the 
functions which are regulated through this system are dis- 
turbed. The hand becomes unsteady, the eye less sure. An 
archer or rifleman has often had his skill fail through the 
effect of tobacco. Athletes in trainino- are forbidden its use. 



TOBACCO - OPIUM — COCAINE 237 

The sickness, faintness, dizziness, and vomiting which 
often accompany the first trials at the use of tobacco onglit 
to be a warning of its poisonons natnre. But if this fails 
to deter a boy or man from the practice, the knowledge 
that it stunts the growth, lessens the strength, injures the 
mind and the power of endurance, should do so. 

Statistics made among large numbers of men in the great 
seats of learning of the world tend to show that a large 
proportion of the rankholders are tobacco abstainers. If 
men who have got their development find that tobacco is 
injuring their health, they can stop the use, provided their 
craving for it has not become stronger than their wills, 
and may regain their health. But the boy who has hin- 
dered the growth of his bones and brain and muscles by the 
use of tobacco can never gain the development wliich he 
has lost. There is a time for development, which he has 
wasted, and for every year of that time which he has mis- 
used he must pay during his whole life. He has left only 
so much room for strength, and work as he may in later 
years he can never reach the strength which he might have 
had if he had not hindered the growth of his organs in 3'outh. 

Opium is a gummy substance which contains several poi- 
sonous constituents, as morphine and codeine. Laudanum 
and paregoric are familiar preparations of this substance. 

Man 3^ people take it first for the relief of pain, and get in 
the habit of using it, so that when they try to stop the}^ 
find that they cannot. They have formed what is known as 
the opium habit. For, like alcohol, this substance forms a 
'^ habit" in the consumer, so that after he has taken it for 
some time he is unhappy and even ill without it. If he 
continues to take it, it mil destroy his health, his capacity 
for work, and finally his mind. He lies, steals, and com- 
mits other crimes without compunction. 

The effect of a single dose of opium or morphine is to 



238 PHYSIOLOGY AND HYGIENE 

cause a diminislied sensibility, to allay pain, and to produce an 
unnatural sleep. A person who has taken it once is tempted 
to try it again and to take it for all sorts of pain, and thus 
he finally forms the opium habit. 

The use of opium as a habit is less common with us than 
in some Eastern countries, but it is too common. 

Some other substances which are used for the relief of 
pain are chloral and cocaine. 

The use of chloral may lead to the chloral habit. It is used 
by peoj^le to procure sleep as well as to relieve pain. 

Cocaine is likewise used to relieve pain, and leads to the 
cocaine hahif, which is very difficult to cure. 

In addition to the above drugs there are several other so- 
called medicines against the indiscriminate use of which 
people should be warned. Among these are phenacetine, 
antipyrine, and many other headache medicines. These 
medicines may relieve the trouble for the time, but they are 
dangerous. In getting rid of the headache you may get some 
new disturbance from the poisonous action of the drug. 

Many of the patent medicines for the relief of cough or 
pain contain opium. There is but one safe rule, which is to 
take medicines only under a physician's advice. You will 
suffer less in the end from taking no medicine than from 
the use of medicines without professional advice. 

QUESTIONS 

Is tobacco ever useful from the point of vievr of the body needs? Is 
it ever harmful? What are its effects upon the membranes of the 
throat and air passages? What may the effect of smoking be upon the 
nutrition of the body if practiced during the period of growth? What 
are the dangers attending the use of opium? Of cocaine? What are 
the objections to taking drugs without a physician's advice? 



CHAPTER XIII 

THE SPECIAL SENSES 

Sensation. When any impulse is brought by the afferent 
nerves to the brain from any part of the body and causes a 
feeling there, a consciousness that something is happening, 
we call it a sensation (Latin sentire, "to feel, perceive"). 
Thus, when a piece of ice touches the hand we have a sen- 
sation of cold. When sugar is placed upon the tongue we 
have a sensation of taste. 

Some sensations are very definite. We can localize the 
part of the body from which they come, and can recognize 
the object which causes them. Such are the sensations of 
touch, of pain, of cold, of sight. When anything touches 
the hand, Ave have the sensation of touch; we know where 
the touch takes place, and we may be able to tell from the 
special nature of the sensation what the object is which is 
touching us. 

Other sensations are indefinite in their character and 
localization. Such are the sensations of hunger, of mental 
pleasure, of fatigue. We cannot say that these sensations 
come from a particular part or a particular outside object. 

The special senses. A large proportion of our definite 
sensations come to us through what are known as the special 
senses. Almost all our knowledge of the outer world comes 
to us through these. 

239 



240 



PHYSIOLOGY AND HYGIENE 



The special senses are usually described as five in number, 
sight, hearing, touch, taste, and smell. To these must be 
added the sense of temperature, the sense of pressure, and 
perhaps the muscular sense. 

All of these special senses have special organs in which 
the sensory impulses originate. 

Sense organs. Each special sense organ may be placed in 
a special part or may be distributed in several parts. Thus, 
sight is located in the eyeball, hearing in the ear. The 
special organ of touch may be located in the skin or in the 
mucous membranes. Taste has a special nerve organ lo- 
cated in the mucous 



|ft^«?S^MS 



of the 



membrane 
tongue. 

The special sense 
impulse originates 
in the special organ, 
and is carried by 
the nerve from that 
organ to the brain, 
where the sensation 
occurs. 

Touch. The or- 
gans of the sense 
of touch are located 
in the skin and in 
some mucous mem- 
branes. In some pa- 
pilla of the dermis 
are placed small oval structures composed of cells from 
which a sensory nerve arises. These oval structures are 
called the tactile (Latin tangere, ''to touch") corpuscles. 

Some of the fine endings of these nerves of touch run 
even into the cells of the ej^idermis. The organ of touchy 




Tactile corpuscle in the skin. 



THE SPECIAL SENSES 



241 



however, is always the cells over a nerve ending, not the 
nerve itself. The touch of the nerve end itself causes pain, 
not the distinguishing sensation of touch. This sensation 
not only tells that an object touches us, but also the char- 
acter of the object, whether hard or soft or rough. 

This sense is most delicate at the tips of the fingers, the 
tip of the tongue, and on the face. It is least delicate upon 
the back, owing to the smaller 
number of tactile corpuscles 
there and the thicker epider- 
mis. If we place the two points 
of a compass one tenth of an 
inch apart upon the tip of the 
finger or tongue, we can feel 
each point ; upon the back, the 
points even two inches apart 
feel as one point. 

The sense of temperature al- 
so is placed in the skin. This 
sensation arises from special 
organs distinct from those of 
touch. ^ The fact that these 
sensations of touch, pain, and 
temperature, which are received 
in the skin, are carried by sep- 
arate nerve fibers, is demon- 
strated by certain diseases. 
Thus, there is a disease of the 
spinal cord in which the patient "nir^l^r^.^^t^m^ ' 
loses the sense of pain, but not 

that of touch, in a certain part ; also one in which the sense 
of touch is lost, while that of pain is intact. 




1 This sense can be cultivated. The blind by training acquire a very delicate sense 
which enables them to.distinguish by touch objects which to our sense are alike. 



242 



PHYSIOLOGY AND HYGIENE 



Taste. The organs of the sense of taste are located in the 
mncous membrane of the tongue and pahxte. This mem- 
brane is raised into numerous elevations, or papillae. In 
these papillae are the endings of the nerves of taste. 

The papillaB are of three kinds. The Jil if orni {hsitui filum, 
"thread," smd forma, ''form'') papillae are long and slender, 
and placed over the front of the tongue. They contain the 
organs of the sense of touch in the tongue. The fungiform 
(Latin fungus, " mushroom ") papilla? are mushroom-shaped, 
with broad crowns and slender stems. The circuni vallate 
(Latin c/rc?r»^, "aroiuid," and valJuni,^^Si trench") papillae 
are large mound-shaped papillae with a ditch or moat about 

them. They are sit- 
~\Y'ZZ^^^^^^^J"~ — ^^^T^^^^^^yr uated in double rows, 
""^ ^^ forming a V on the 

back of the tongue. 
These fungiform and 
circumvallate papillae 
contain the taste huds. 
Each taste bud is 
made up of epithelial 
cells arranged like the 
petals of a rosebud, 
the inner cells having 
fine processes reaching to the surface of the papilla. The 
fine nerve ending of tlie glossopharyngeal nerve of taste 
runs into these inner cells. When sugar is placed upon the 
tongue the fine processes of the buds are stimulated, and 
this sensation is transmitted by the nerve to the brain. 

Tastes. These taste buds have to act for four kinds of 
taste— sweet, bitter, sour, salt. With most people the bit- 
ter tastes are perceived at the back of the tongue, the sweet 
at the tip. Substances to be tasted must be in solution. 
When the mouth is dry, as in fevers, the taste is very weak. 




Taste buds. 



THE SPECIAL SENSES' 243 

Many so-called tastes are flavors, and are really distinguished 
by the sense of smell. Such are the flavors of meat or vege- 
tables. If we hold the nose when we eat an onion we cannot 
tell what we are eating. 

Smell. The organs of the sense of smell are situated in 
the mucous membrane lining the upper part of the cavity of 
the nose. The outer openings of the nostrils, which we see, 
lead to the nasal chambers. Behind, these chambers open 
into the pharynx. Into these chambers from the sides pro- 
trude three spongy, scroll-like bones, the turbinates. Over 
the wiiole inner surface of the chambers lies a mucous 
membrane. In this membrane in the upper chambers many 
of the epithelial cells on the surface are rod-shaped. To 
these rod-shaped cells the nerve endings of the olfactory 
nerve go. Any odor which floats in the air and is drawn 
through the nose stimulates these rod cells, and produces the 
sensation of smell. The lower part of the nostril near the 
opening is lined with columnar cells having cilia. 

The air is warmed in passing through the nose to the 
lungs. It takes up moisture from the walls. It is freed 
from dust and bacteria by the hairs at the entrance to the 
nostril. 

The sense of smeU is often useful in enabling us to dis- 
cover the presence of noxious substances, as decaying mat- 
ter, coal gas, etc. 

The sense of sight. The organ of the sense of sight is 
the eyeball. The eyeball is a globular structure lying in the 
bony orbit of the skull. It is placed well forwa-rd in the 
face so that all objects in front or at the sides of the head 
will come in sight of it. At the back it is connected with 
the brain, so that it may be called a bay window of the 
brain, thrown out to command a clear and full view of the 
world about. 

The eyeball is covered in front by the eyelids. These lids 



2U PHYSIOLOGY AND HYGIENE 

are curtains whicli may be raised or lowered before the eye 
to protect it from light or dust. Tliey are made up of 
fibrous connective tissue lined with skin on the outside, and 
on the inside by a membrane of thin epithelial cells, the cou- 
pmctiva. Tliis membrane lines the inside of the lids and 
passes from these over the front of the eyeball. At the 
edge of the lids are the eyelashes, which serve to keep dust 
from the eye. 

The lids contain striate muscle and can be opened and 
closed at will. When a strong light strikes the eye they 
close by a reflex, as described in the chapter on the nervous 
system. 

Motions of the eyeball. The eyeball is moved by six mus- 
cles which attach to the walls of the orbit. One muscle, the 
external rectus, turns the ball outward, as when we look off 
to the right with the right ej^e. The internal rectus turns 
the ball in toward the nose. The superior rectus turns the 
ball upward, the inferior rectus downward. Two other 
muscles, the superior and inferior oblique muscles, aid in turn- 
ing the eye. 

When we look at a near object close to the nose, the inter- 
nal rectus of each eye contracts and points both eyeballs 
inward. 

Each orbital cavity is padded with fat, which makes a soft 
cushion for the eyeball. At the outer side of each orbit is 
a small gland, the lachrymal (Latin lachtijma, " a tear ") gland, 
which secretes the tears. This gland is continually secret- 
ing a small amount of fluid w^hicli washes the front of the 
eyeball and di'ains away by small lachrymal ducts to a cis- 
tern sac, which empties it through the nasal duct to the 
cavity of the nose. 

The structure of the eye. The eyeball is a sphere with a 
prominent bulging portion in front; that is, it consists of 
the segments of two spheres. The front bulging part, 



THE SPECIAL SENSES 245 

through which we see the mottled-colored ring and the dark 
circle in the center, is the cornea. This is attached all about 
to the white coat of the eye, the sclera (Greek sMeros, 
''hard"). The cornea and sclera are made up of fibrous 
material, and together form the outer coat of the eye. 

Just inside the cornea, and seen through it, is a colored 
ring, the iris, inclosing a dark circular opening, the pupil 
Between the cornea and iris is a clear watery substance, 
the aqueous (Latin aqua, " water ") humor. 




Plan of eyeball. 

O, optic nerve ; 72, retina; F, vitreous humor; L, lens; O, cornea; (7on, conjunctiva; 
Sc, sclera; /, iris; A, aqueous humor; Cin, ciliary muscle ; Ch, choroid. 



The iris is differently colored in different people. Thus 
we have blue eyes or gray eyes. The iris contains muscle, 
and can contract and dilate, changing the size of the pupil. 
The iris is continuous with a second coat of the eye, which 
runs inside the sclera, the choroid. Tliis choroid coat, at 
its junction with the iris, is thrown into folds, like the 



246 PHYSIOLOGY AND HYGIENE 

tucks of a dress. These folds are called the ciliary (Latm 
ciliiDii, ''hau'") processes. The choroid coat carries blood 
vessels to feed the eye. Its inner layer is black, being lined 
with pigment granules. 

The 2^upil is a circular opening bounded by the iris. At 
the back of this opening is the crystalline (Greek I'r us f alios, 
"clear ice") lens. This is a double convex, transparent 
structure, like the lenses of magnifying glasses. It is held 
by a sheet ligament from the choroid, the suspensory (Latin 
suh, "under," and 2)e)idere, ''to hang") ligament. 

At the back of the eye, behind the lens and inside the 
choroid coat, is the third coat of the eye, the retina (Latin 
rete^ "a net"). This is a thin membrane in which the libers 
of the optic nerve, entering through the walls of the eyeball 
behind, radiate in all directions. Between the lens and the 
retina is a clear fluid substance, i\\Q vitreous (Latin vitrutn, 
" glass ") humor. 

Structure of retina. The retina is reaUy an expansion of 
the optic nerve, with structures ):>uilt up upon it to receive 
and transmit the impressions of light, which come froin with- 
out through the pupil and lens, on to the brain in such a way 
that we get there an image of the thing before our eyes. 
- These stru(^tures which receive the light impressions are 
known as the rods and cones. Over the whole surface of the 
retina is a layer made up of numerous rodlike cells, with 
tapering threadlike processes running toward the front of 
the eye, and of sugarloaf-shaped bodies with short processes, 
the cones. The processes of both rods and cones give out 
delicate threads which run to cells deeper in the retina, and 
these again attach to the fibers of the nerve. The structures 
of the retina are laid down in eleven layers. The nerve 
layer is in front. The light passes in through all these 
structures to the layer (^f rods and cones. Here the im- 
pression is taken and the cell processes set vibrating. This 



THE SPECIAL SENSES 



247 



vibration is transmitted from the rods and cones to the 
nerve fibers, and thns to the brain« 



Outer or churuidal surface 




I, Layer of pigment cells 



7 ( aycr of rods and i 



.. . Memftrana limitans externa 



Outer nuclear layer 



Outer molecular layer 



4. Inner nuclear layer 



3. Inner molecular layer 



2. Layer of nerve cells 



1. Layer of nerve fibers 

.Membrana limitans interna 



Inner surface 



Section of retina. 



In the center of the retina is an oval spot, the yellotv spot. 
Here the laj^ers of the retina, except the layer of the rods and 

HEWES, P. & H, — 16 



248 PHYSIOLOGY AND HYGIENE 

cones, are thin, and the cones are, contrary to the condition 
elsewhere, thicker than the rods. This is the part of the 
eye where the image strikes when we look straight at an 
object so as to get the clearest vision of it. 

The blind spot. There is one part of the retina where 
the optic nerve passes through it from the back to the ante- 
rior surface of the retina, where it spreads out. This spot 
has no rods and cones, and therefore takes no impressions. 
It is called the blind spot. This spot can be found by the 
following experiment : Place upon a piece of paper a cross 
and a round black spot, three inches apart, as upon this page : 



^ 



Hold the sheet about twelve inches in front of the eyes. 
Close the left eye and look at the cross with the riglit ; you 
will see the dot at the same time. Move the sheet slowly 
toward you, keeping the right eye fixed upon the cross. At 
a certain distance from the eye the dot will disappear, and 
wiU reappear as the sheet is brought still nearer. When the 
sheet is at the place where the dot cannot be seen, the light 
from the dot is falling upon the blind spot. When the 
sheet is farther or nearer, the light is upon the retina to the 
right or left of this. 

Mechanism of sight. The coats of the eye, the sclera and cho- 
roid, serve to carry vessels for the nourishment of the retina, 
and also for protection and for the formation of a chamber 
for the reception of the light images. The refracting media, 
—the aqueous humor, the lens, and the vitreous humor,— the 
cornea, and the accommodation (Latin accommodo, ''adapt") 
mechanism of the iris are for the purpose of bringing the 
rays of light upon the retina in such a way as to form a clear 
image of the thing seen. The cornea and refracting media 
of the eye collect the rays of light from the object seen, and 



THE SPECIAL SENSES 249 

foous these rays upon the retina. In this way an inverted 
image of the object is formed upon the retina. The lens and 
other refracting media simply bend the rays of light from the 
object seen in such a manner that they all fall within the space 
of tlie retina, so that, unless it is too near, a very large ob- 
ject can be focused upon the small area of the retina. Light 
consists of vibrations of the ether. When these waves of 
vibration strike the convex surfat^e of the refracting media, 
they are bent inward. The amount of bending depends 
upon the convexity of the lens. If the object is near the eye, 
the rays need to be more bent to focus upon the retina ; that 
is, we need a very convex lens. If the object is far away, the 
rays need less bending and the lens must be less convex. 
That we can focus both near and far objects perfectly in our 
eyes is due to the faculty of the eye of changing the convex- 
ity of the lens. This is known as accommodation. 

The mechanism of accommodation is regulated by the 
action of the ciliary muscles of the lens supports. The lens 
is an elastic body which tends naturally to take a very con- 
vex shape. It is inclosed in a capsule, to Avhich is attached 
the suspensory ligament. The ligament is so adjusted that 
when the ciliary muscles of the choroid processes contract, 
the ligament is slackened and the lens is free to take its 
natural shape. This occurs when we accommodate the eye to 
a near object. When the muscles relax, the ligament is 
drawn tight, pulling on the lens capsule and flattening the 
lens, so that it is less convex. This occurs when we look at 
a far object. 

Short and long sight. Most people cannot see objects 
clearly which lie nearer than five inches from the eye. 
This is because the lens cannot be made convex enough to 
focus all the rays from such an object upon the retina. The 
rays from the sides of the object go by. Some people, how- 
ever, see close objects better than more distant ones. These 



250 



PHYSIOLOGY AND HYGIENE 



are shortsighted people. Their peculiarity is due to the 
fact that the retiua is farther off thau normal from the 
lens, so that near objects can be bent to it. Owing to this 
distance of retina from lens, these people cannot focus a 
distant object. No matter how much the lens is flattened 
it focuses ill front of the retina, where the normal retina 
would be. To correct this difficulty such people have glasses 
made with a concave lens. This throws the rays outward 
and causes them to focus farther back. 

In a long-sighted person the ball is shorter than the rule, 
and near objects focus behind the retina. An additional 
convex lens has to be used to correct tliis. 




Diagram of refraction, 
o, object; b, lens; c, image upon retina. 



Action of the iris. The lens is not a perfect instrument. 
Some of the rays are brought to a focus in front of most of 
the rays. To remedy this defect the eye is provided 
with the iris curtain. This curtain shuts off more or less 
of these rays which do not focus on the retina, and thus 
leaves a clear image there. The amount of light which 
must be cut off differs with the distance of the image. If 
the image is near, much light is cut off ; if distant, little 



THE SPECIAL SENSES 251 

light. To meet these varying conditions the iris is made to 
grow larger or smaller, so that when an object is far away 
the iris is pulled back and the pupil is large, and when the 
object is near the iris closes and the pupil is small. You can 
see the pupil change if you watch the eye of some one who 
is looking at your finger as you draw it gradually away from 
his face. To change in this way, the iris is provided with a 
sphincter (Greek spMggeiu, "to contract") muscle which 
contracts it, and other muscles which draw it back. 

The formation of a clear image in the eye may be illus- 
trated by the following experiment: In a dark room fix a 
lens a few feet in front of a candle flame. If a sheet of 
paper is held at the right distance in front of the lens a 
clear inverted image of the candle flame will appear upon 
the paper. The paper here represents the retina of the eye, 
the lens the refracting media. If the candle were held 
before the eye, the image would appear upon the retina as 
upon the paper. 

Now, if the candle is held nearer the lens, the image upon 
the paper will grow indistinct. To get a clear image we 
have to move the paper awa}^ from the lens or replace the 
lens by a stronger, more curved one. In the eye the latter 
method is adopted ; the lens is made more convex by the 
mechanism of accommodation. If the candle is moved 
farther from the lens, the paper has to be moved nearer to 
get the clear image, or the lens made weaker, less curved. 

You can demonstrate this action of accommodation in 
your own eyes by the following experiment: Place two 
pegs in a board, one about a foot from the end and the other 
eighteen inches farther away. Close one eye, and with the 
other look along the board with the pegs nearly in a line. 
If you look at the farther peg this will be clear and the 
nearer indistinct. If you accommodate to the nearer, the 
farther will be indistinct. 



252 PHYSIOLOGY AND HYGIENE 

Hygiene of the eye. The eye, like all the organs of the 
body, can be trained by exercise. Constant practice in shoot- 
ing, in ball playing and tennis, gives a man what is known 
as a true eye. A trained eye compared with an untrained 
one is like a high-power microscope compared with one of 
lower power. And yet the eye is only the instrument; it is 
the mind that sees. While the more perfect the instrumeut 
the more the mind can see, yet a keen mind is necessary to 
a keen eye.^ 

The eye suffers from improper exercise or overwork, and 
want of care. A child must hold the book which he is read- 
ing at the correct distance from the eye, neither too near 
nor too far, else he will strain the apparatus of accommoda- 
tion. He must read with proper light, and with the bright 
light behind him. Disregard of these precautions may lead 
to impaired eyesight for life. 

In school the desks should be so placed that the light 
comes from the rear or the side. A cross light which daz- 
zles the eye should be avoided by means of window shades. 
The pupil nmst not sit with the head and body bent for- 
ward over the desk while reading. Well-printed books with 
type of good size should be chosen. 

At home the child should never read by candlelight or 
by light from any flame which flickers. Eeading in bed 
while lying upon the back is a bad plan. Reading in the 
cars, where the book is being constantly jolted, is harmful ; 
it tires the muscles of the eyeball and of accommodation. 

Objects which get into the eye should be carefully 
removed. The eye should not be rubbed in such instances 
or upon any occasions when it smarts or tingles. 

' The eye is the most expressive part of the face. However pronounced the smile 
about the mouth, if it is unaccompanied by a kindly light from the eyes it has an un- 
pleasant effect. So responsive are the muscles about the eyes to the thoughts of the 
mind that the lines formed there by their habitual position come to show the kind 
of thoughts that the mind harbors most, and thus character is revealed by the face. 



THE SPECIAL SENSES 253 

If cliildren are found to be nearsighted or farsighted 
they should be placed under the direction of an oculist. 
People may injure themselves by wearing glasses when they 
do not need them or by wearing improper glasses. They 
should get their glasses in accordance with the advice of a 
competent physician. 

As people grow old changes occur in the lens which limit 
its accommodation. It cannot be made so convex as before 
to accommodate to near objects. When this trouble ap- 
pears, glasses should be worn fitted to the eyes. 

The signs of eye strain are apt to be sharp neuralgic 
pains about the eyes and a sense of fullness in the eyeballs. 
When these signs appear regularly after reading the eyes 
should be examined.^ 

The effect of alcohol upon the eyes is seen in the blood- 
shot conjunctivae and relaxed watery lids of topers. Alco- 
hol may cause disease of the retina, with marked disturb- 
ance of vision .2 

Tobacco smoking tends to bring about inflammation of 
the conjunctivae and lids by the irritation of the smoke. 
The absorption of poison from constant smoking may bring 
on a diseased condition of the retina, resulting in diminu- 
tion or even loss of vision. 

HEARING 

Sound is caused by the vibrations of a substance. When 
a bell rings, the vibrations of the metal set up waves of 

1 Little children shoiild not be allowed to loot at very fine objects with the head 
down. The use of printed books before a child is eight years old is a menace to the 
eyes. Students should make it a rule to stop for a few minutes at the end of every 
hour to rest the eyes. In very close work a stop should be made every ten minutes 
after a person is thirty years old; a few seconds will suffice. 

2 Drs. Nicol and Mossop of Edinburgh conducted a series of experiments on each 
other, examining the eye by means of the ophthalmoscope while the system was tinder 
the influence of various drugs. They found that the nerves controlling the delicate 
blood vessels of the retina were paralyzed by a dose of about a tablespoonf ul of brandy. 



254 



PHYSIOLOGY AND HYGIENE 



vibration in the air, which are transmitted to the ear. When 
these vibrations in the ear are taken up by the sense organ 
and converted to nerve impulses, which are carried to the 
brain by the auditory nerve, we have the sensation of sound. 
We hear the bell ring. 

The organ of hearing is the ear. The ear consists of the 
external ear, the middle ear, and the internal ear. 

The external ear consists of a cartilage shell covered by 
connective tissue and skin. This shell collects the sound. 



External ear 



Semicircular 
canals 




Section of ear, showing auditory canal, middle ear, 
internal ear, and Eustachian tube. 



From this outer shell a canal runs inward into the temporal 
bone. At the inner end of the canal is a membrane, the 
tympanum, which stretches across the canal and shuts it 
off from the middle ear. The canal is lined with skin, and 
a substance called wax is secreted in it from glands in its 
walls. 

The middle ear is a cavity in the temporal bone. The 



THE SPECIAL SENSES 255 

drmn, or hjmpanum (Greek timipanom, " a drum "), shuts it off 
from the outei* ear. Froin its inner side a tube, the Eusta- 
chian tube, k'juls to the upper part of the pharynx. We can 
feel the air go into the ear by tliis tube sometimes when we 
swallow. 

In tli(^ inner wall are two openings, the fotestra (Latin 
fenestra, "window") ovalis ("oval") and fenestra rotunda 
("round"), which lead to the cavity of the inner ear. They 
are closed eacli ])y a membrane. 

Stretching from the tympanum to the fenestra ovalis 
across the middle ear is a chain of three small bones. The 
first is shaped like a hammer and is called tlie malleus (Latin, 
"mallet"). The handle of the hammer attaches to the 
tympanum, the claw to the wall of the cavity, the head to 
the next bone, the incus. 

The incus (Latin, "anvil") is anvil-shaped. The head 
articulates with the hammer, one process with the wall, and 
one witli the third bone, the stapes. 

The stapes (Latin, "stirrup") is stirrup-shaped. The top 
of the arch attaches to the incus; the foot plate fits into the 
fenestra ovalis against the nn^mbrane there. 

Two muscles attach to these bones— one to the hammer 
handle, which by contracting tightens the drum of the ear, 
another to the arch of the stirrup, which tightens the menu 
brane of the fenestra ovalis. 

The internal ear is a cavity in the temporal bone. It con- 
nects with the middle ear by the two fenestra openings, 
which are covered by membranes. In this cavity lies a 
membranous sac filled with fluid and floating in fluid, which 
fills the cavity. The sac is attached to the walls of the 
cavity in several places. This sac contains the essential 
organ of hearing, by which the vibration waves of sound 
are taken up and transmitted to the ear. 

The sac, or membranous labyrinth, consists of several cham- 




256 PHYSIOLOGY AND HYGIENE 

bers. The middle cliainber, the vestibule (Latin vestihulum), 
lies opposite the fenestra ovalis, where the sthTup bone 
of the middle ear abuts. From the 
vestibule open three canals, the semi- 
circular (Latin semi, "half," and cir- 
cularej " to encircle ") canals, which are 
closed tubes circling round and return- 
ing to the vestibule again. One canal 
has a horizontal position, two have a 
vertical position. At the end of each 
and cochlea caual is a bulb attached by fibrous 

tissue to the bone. At these bulbs, 
branches of the auditory nerve enter. From another part 
of the vestibule a tube in the form of a spiral coil with a 
blind end is given oif. This is the cochlea (Latin, "snail"). 
The membrane of the ear sac, the vestibule, canals, and 
cochlea is made up of connective tissue lined within by 
epithelial cells. In patches over the walls of the canals and 
cochlea are collections of cells known as the andifory (Latin 
audire, "to hear") epitlieJium. The cells which make up 
these patches are cylindrical and spindle-shaped, and have 
processes projecting into the lymph which fills the sac. The 
ends of the auditory nerve, which enter the sac at the bulbs 
of the canals and in several other places, connect with these 
ceUs. A special tract of this auditory epithelium is situated 
in the cochlea. It is called the organ of Corti. 

The nerve fibers end here in cells known as hair cells, which 
are placed in rows beside a central row of rod-shaped cells. 

The sac is filled with a fluid called the endohfmph (Greek 
endon, " within," and Latin hjmplia, " water "). About the sac 
in the bom^ cavity is a fluid, the jjerilijmph (Greek j)eri, 
"around" ). This perilymph lies against the fenestra ovalis 
on one side of the cochlea and igainst the fenestra rotunda 
upon the other. 



THE SPECIAL SENSES 257 

Transmission of sound in the ear. The waves of sound are 
collected by the external ear, pass in through the external 
canal, and set the tympanum in vibration. This vibration 
is transmitted by the three bones, the malleus, incus, and 
stapes, to the fenestra ovalis. Here the vibration is trans- 
mitted to the perilymph, and thus to the walls of the vesti- 
bule, canals, cochlea, and endolymph. The vibrations of 
the endolymph agitate the cells of the auditory epithelium, 
especially the hair cells of the cochlea, and are trans- 
mitted by these to the nerve endings, and thus to the brain, 
where the sensation of sound is aroused. 

Character of sound. Sounds differ according to the char- 
acter of the vibrations which are set up in a body. When a 
bell is struck the vibrations follow each other at regular 
intervals, and the sound is called a musical sound. When 
a lot of crockery falls the vibrations are irregular, and we 
call the sound a noise. 

Pitch. What is called the pitch of a sound dependfe upon 
the number of vibrations in a given time. If the vibrations 
follow one another slowly the pitch is low; if they follow 
rapidly the pitch is high. The ear can perceive notes of a 
pitch so high that the vibrations occur from twenty to thirty 
thousand in a second, or so low that the vibrations are thirty 
a second. 

Hygiene of the ear. The acuteness of the ear may be 
trained. The Indian of the forest hears sounds which we 
cannot hear. The trained musician distinguishes notes and 
pitch much more accurately than an ordinary person. 

No one should ever shout close to a person's ear, or set 
off a firecracker or pistol near the ear, as the sound may 
produce serious injur^r. Hairpins and other articles should 
not be put into the ears to relieve itching. They inflame 
the canal and may puncture the drum. 

Children not infrequently have so-called gatherings in 



258 PHYSIOLOGY AND HYGIENE 

the middle ear cavity. This is an inflammation of the 
membrane of the cavity. The fluid which is exuded by the 
inflammatory process often bursts the drum and discharges 
by the outer ear. In babies who are feverish and restless 
we should always think of this trouble. Where the trouble 
is suspected a physician should be called at once. 

Children with adenoids or large tonsils are apt to have 
trouble with the ears. These abnormal growths should 
therefore be removed at an early age. 

Tobacco smokiug, by inflaming the throat, often causes 
irritation about the openings of the Eustachian tubes from 
the ears, thus diminishing the circulation of air in the middle 
ear and making the part more subject to disease. 

The muscle sense is the perception which we have of the 
position of a limb or a part of the body. The organs and 
nerve endings of this sense are situated in the muscles and 
in the tissues about the joints. 

The pressure sense is the perception which we have of 
the weight of an object. The nerve endings in the skin and 
muscles of the region supporting the weight transmit the 
impression to the brain. 

DEMONSTRATIONS AND EXPERIMENTS 

A number of experiments to illustrate the phenomena of the special 
senses have been given in the course of the chapter. 

1. The organs of the sense of touch are very numerous in some parts, 
as upon the finger tips or upon the end of the tongue. Here you can feel 
both points of a compass even when they are but an eighth of an inch 
apart. In other parts, as the back, however, the sense of touch is 
much less acute. Here the two tips of the compass often feel as one 
object even when three fourths of an inch apart. 

2. Determine the relative sensitiveness to touch of the palm and back 
of the hand, the forehead, the back of the neck. (Use a hair.) 

3. Determine what is the least distance that the two points of a com- 
pass may be separated and still recognized as two when applied to the 
finger tip, the tongue, the back of the neck. 



THE SPECIAL SENSES 259 

4. Place a drop of vinegar upon the tongue. Note how it starts np the 
papilli© into prominence. 

Note that sugar is tasted best at the front of the tongue ; salt or 
aloes at the back. 

5. Hold the nose and close the eyes while some one puts a piece of 
apple or potato into your mouth. You will be unable to tell which 
you have received, as the so-called taste of these substances is in reality 
a sensation of smell. 

6. With a common hand lens (a burning glass) throw the image of a 
window upon a sheet of paper. This represents the mechanism by 
which the image of an object seen is thrown upon the retina. 

7. Look through a pinhole at a bright light with a shade about it. The 
specks which you will note floating before your vision are made by 
opaque particles floating about in the vitreous humor in front of the 
retina. 

8. Accommodation. Close one eye. Hold up both forefingers, not ex- 
actly in line, one six inches from the open eye, the other about eighteen 
inches away. Look at the near finger. A clear image of this is ob- 
tained, while the farther one is indistinct. Now look at the far finger. 
This now becomes distinct, while the near one becomes indistinct. 

9. Place a watch between the teeth. Note that the ticking is readily 
heard with both ears closed. The sound is conducted by the solid bone 
of the jaws. 

10. Place the right forefinger in hot water, the left forefinger in cold 
water. Note the difference in the sensations. 

11. Determine which of the following substances stimulate the sense 
of taste and which that of smell, which are recognized by their taste, 
which by their odor : sugar, onion, cabbage, dilute ammonia (one drop 
to six ounces), quinine, salt, vinegar. 

12. The formation of an image upon the retina can be illustrated with 
the eye of a white rabbit. 

13. The formation of an image upon the ground glass of a camera, and 
the influence of focusing upon the clearness of the image, may be 
demonstrated with a photographic camera. 

14. The color vision of the pupils may be tested with different-colored 
worsteds. 

QUESTIONS 

I. What is sensation? Through what channels do we become aware 
of the world about us? Name the special senses. Where are the organs 



260 PHYSIOLOGY AND HYGIENE 

of touch located? Where is the sense of touch located? How does 
the knowledge that we are touching anything get to the brain? Where 
are the organs of the sense of taste? Describe the papillae of the 
tongue. 

II. ^ATiere are the organs of the sense of temperature located? What 
is the difference between a taste and a flavor? Has an onion any taste? 
Where are the sense organs of smell? What is the function of the 
eye? When we get a sight of any object, where do we really see it ? 
Of what use are the eyelids ? 

III. Why is the eyeball so prominent? Why is it movable? Where 
are the tears secreted? What is the white of the eye? What in reality 
is the dark center of the eye which we call the pupil? What is the part 
of the eye which gives it its color? What object lies at the back of the 
pupil? 

IV. When an object comes before us, what does the eye do? Where 
is the image of the object cast ? When an image strikes the retina, what 
happens in the brain? Of what use is the lens of the eye? To what 
part of a photographic camera does the retina correspond? 

V. What is the use of the iris? What is meant by the blind spot? How 
is it arranged that the image of so large an object as a house can be 
cast upon so small a surface as the retina? What happens to the lens 
when the object is very near the eye? Very far away? Describe this 
mechanism of accommodation. How can we avoid straining the eyes? 

VI. What is sound? Describe the three parts of the ear. Which is 
the most important part? Trace the sound waves from a bell to the 
brain. What is the difference between a musical sound and a noise? 
What is pitch? 



CHAPTER XIV 



THE VOICE 



BY the action of tlie inspired and expired air in setting 
lip vibration of the folds of membrane in the larynx 
called the vocal cords, the sounds are produced which we 
call the voice. 

The larynx consists of a framework of cartilages articu- 
lated together to form a chamber in the course of the air 
tube between the lungs and the nose 
and mouth. Stretched across tliis 
chamber are the vocal cords, and 
the air passino- these cords can be 
made to vibrate them at will. 

Just above the last incomplete 

Cricoi 

cartilage ring of the trachea we have 
the first cartilage of the larynx. 
This is a complete ring, narrow in 
front, broad behind, like a signet 
ring. It is called the cricoid (Greek 
JcriJios, "a ring") car^iZa^e. Above 
this is a V-shaped cartilage with ' 
broad sides, the thyroid (G-reek tJiu- 
reos, '^ a shield "). The open part of 
this cartilage is filled in by the broad posterior part of 
the cricoid. At the back of the larynx, on each side of 
the broad part of the cricoid, is a small cartilage, the aryte- 

261 




Larynx. 




16J PHYSIOLOGY AND HYGIENE 

noid (Grreek arutaina, "a pitclier"). Attached to the top of 
the thjToid is the epiglottis, which closes the entrance be- 
tween the larynx and pharynx. These and several smaller 
cartilages, joined together by connective tissue and muscles, 
make up the larynx. 

The inside of the chamber is lined with a mucous mem- 
brane continuous with that of the pharynx above. Running 
across the tube from the arytenoids at the back to the thy- 
roid at the front are two bands of 
elastic tissue covered by the epi- 
thelium of the larynx. These are 
the rocal (Latin vox, '' voice ") cords. 
Through the V-shaped interval be- 
tween these cords, narrow in front, 
broad behind, the air passes. 

^, , , When the cords are relaxed, the 

Vocal cords. ' 

air passes by freely and does not 

cause them to vibrate ; but if the posterior ends are drawn 

together, the interval between the cords is reduced to a 

narrow slit, and the air passing through sets up vibrations 

in them, producing sound. This is what occurs in voice. 

Mechanism of voice. By the action of muscles which attach 
to the cartilages and move them upon one another, the pos- 
terior ends of the cords are brought together. The cords 
at the same time are tightened b}^ another set of muscles. 
Then the air pressed forcibly between the cords causes 
them to vibrate. 

In accordance with the action of these muscles the tension 
of the cords is varied, and consequently the pitch of the 
sound is produced. A low voice sound means a looser cord, 
a high sound a tighter.^ 

1 In the production of a high-pitched sound the whole larynx is raised. This can 
be demonstrated by placing the fingers upon the throat when the sound is made. In 
the production of low tones the air in the chest is set in vibration. You can feel with 
the hand the thrill of this chest \'ibration when a low tone is made. 



THE VOICE 263 

The difference in the character of voices depends upon 
the differences in the sliape of the larynx. Thus, a wo- 
man's hirynx is smaller and the cords are shorter than a 
man's. 

Speech. Speech is produced by modifying, by the shape 
of the pharynx and month cavities, the voice formed in 
the larynx. The mouth cavity is a sonnding box. By 
the action of the tongue and lips the cavity may be varied 
in size and shape, and according to this variation different 
sounds are produced. Thus, to make the sound of the long 
a the mouth is opened wide, the lips drawn back. To make 
the sound of the o the lips are protruded and the cavity of 
the mouth made long. 

The sounds of some consonants are regulated by the lips, 
as p, 1). These are called labials. The consonants t, d are 
made by placing the tongue against the teeth. They are 
called dentals. The consonants k and g are formed in the 
throat by the root of the tongue and soft palate. They are 
called gutturals. 

Hygiene of the voice. Much attention should be directed 
to the training of the voice. A soft, full voice with musical 
sounds should be cultivated. A rough voice, or a nasal 
tone which appears to come from the head, produces an un- 
favorable impression.^ 

DEMONSTRATIONS 

1. A very good illustration of the principle of the action of the vocal 
bands in the production of the voice may be given by means of a piece 
of bamboo or any hollow wooden tube and a strip of rubber about 
an inch or an inch and a half wide, cut from the pure sheet rubber 
used by dentists. 

1 In impatience or anger the voice rises, betraying the loss of temper or self-control. 
Americans have a tendency to a high tone of voice, owing probably to the high nervous 
tension developed by our active business enterprises. It is interpreted abroad as an 
indication of our crudity as a nation. Tlius the term "the American voice " is a kind 
of national reproach, which we should seek to remedy by cultivating purer and lower 
tones, more quiet manners, and self -poise. 

HEWES, P. & H. — 17 



264 PHYSIOLOGY AND HYGIENE 

One end of the tube is to be cut sloping in two directions, and the 
strip of sheet rubber is then wrapped around the tube so as to leave a 
narrow slit terminating at the upper corners of the tube. 

By blowing into the other end of the tube the edges of the rubber 
bands will be set in vibration, and by touching the vibrating membrane 
at different points, so as to check its movements, it may be shown that 
the pitch of the note emitted depends upon the length and breadth of 
the vibrating portion of the vocal bands.— Dr. H. P. Bowditch. 

2. Pinch the nose and speak some words like " something " or " pud- 
ding." This illustrates the usefulness of the nasal cavity as a resonant 
cavity in speech. 

3. The effect of a resonance chamber, as the mouth, can be demon- 
strated by striking a tuning fork and holding it before the mouth and 
before several resonance chambers. 

4. The relation of pitch to rapidity of vibration, and of volume of 
sound to extent of vibration, can be illustrated by a violin, or a piece 
of catgut which is stretched tightly between two fixed points. 



QUESTIONS 

What is the organ of the voice? How are the voice sounds produced? 
How are the voice sounds modified into speech? 



CHAPTER XV 

FERMENTS AND FERMENTATION— THEIR PLACE IN NATURE. 
BACTERIA AND THEIR CONNECTION WITH DISEASE 

With Earth's first Clay They did the Last Man knead, 
And there of the Last Harvest sow'd the Seed : 

And the first Morning of Creation wrote 
What the Last Dawn of Destiny shall read. 

The indestructibility of matter. Everything in .the world 
is in a constant process of change. Mountains which to-day 
lift their snowcapped peaks among the clouds were once 
covered by the sea. Plains and valleys once spread with 
forests and inhabited by men and beasts are now deep be- 
neath the ocean, the abode of the seaweeds and shellfish. 
Once stateh^ cities, the abodes of wealth and power, now lie 
buried beneath the soil piled upon them from their own 
ruins and the ceaseless labor of the earthworms. The water 
which, yesterday fell as rain is to-day a part of the leaf of 
some plant or the blood of some animal, and to-morrow will 
rise again to the clouds. The vegetables or fruit which we 
gather for food will be built up into bone and muscle, and 
in turn be burned until their elements are scattered again 
to the air and the soil. 

Everything is continuously building up and crumbling 
again. The elements of which all things are composed, such 
as the carbon, oxygen, nitrogen, iron, calcium, and hydrogen, 

265 



206 PHYSIOLOGY AND HYGIENE 

alone of all materials upon. the earth, are never destroyed; 
but, forever driven by the ceaseless force which in a thou- 
sand forms everywhere pervades the universe, these atoms^ 
continue their unending journey through the realm of na- 
ture, now taken from the air to form a part of the fiber 
of some moss, now lying for thousands of years stored in 
coal beneath the earth's surface, now restored to the air and 
soil by the burning of this coal ; to-day a part of your bones 
or brain, to-morrow in the petal of some flower or the water 
of some woodland fountain. 

In the mineral world, the rocks and sands, these changes 
occur slowly during years and centuries; but in the world 
of living things, the plants and animals, the changes are 
very rapid and complete. 

Each year millions of plants which grow in the spring die 
and crumble away in the summer and autumn, and thousands 
of men and beasts which have been liuilt up through long 
years are dying and their bodies returning to the dust from 
which they came. Within these Jiving bodies of animals 
new tissues are constantly being built and burned from day 
to day. 

A part of this process of change which goes on in the 
world of living things has been minutely described. We 
have seen how the carbon, nitrogen, oxygen, hydrogen, and 
other elements in the air and soil and water are taken up by 
the plants and built into wheat or potato or some fruit ; also 
how these plant substances are built up to bone and flesh 
in the animal body ; finally how some of these body sub- 
stances are broken up again by l)urninc: in the body, and 
distributed -back to the air and soil. But we have not yet 
learned how these full-grown plants and animal bodies, 
with their fiber and leaf and bone and flesh, are reduced 

1 The word " atom " (Greek a, privative, and temno, " I ciit "—not to be cut) is used 
to describe tlie forms of matter which cannot be further divided. 



FERMENTS AND BACTERIA 267 

again, when they die, to carbon, nitrogen, oxygen, and so 
forth. This has to be done, otherwise the supply of these 
elements in the air and soil would soon become all stored 
up in existing plants and animals, and none be left for the 
building of new ones or the repair of the old. 

Ferments and fermentation. To do this work nature pro- 
vides certain agents known as ferments. These ferments 
which play this important role in the scheme of nature are 
minute living organisms, so small that they can be seen 
only with the aid of a powerful magnifying lens. Because 
they are bodies possessing life they are called organized 
ferments. 

One of these ferments, the yeast plant, has already been 
described in Chapter VII. (see also pp. 274-276). Another 
class consists of the molds which you have often seen 
growing upon old fruit or grain. A third class of organized 
ferments is that of the bacteria. 

The process by which these ferments act in fulfilling their 
work in the scheme of nature is known as fermentatioii 
(Latin fermentitmy^^ leaven"). The decay of fruit or vege- 
tables, the putrefaction (Latin putris, "rotten," and facere, 
"to make") of meat, the souring of milk, the decomposition 
of sugar to alcohol and carbon dioxide, the conversion of 
alcohol to acetic acid, are all examples of fermentation. 

The process is essentially one of decomposition (Latin de, 
'^from," and componere^ "to place together" — breaking apart). 
As we have explained in a previous chapter, the organic sub- 
stances which compose the tissues of animals or plants are 
compound substances. They are made up of simpler chemi- 
cal substances (elements) bound together. These compound 
substances the ferments attack^ feeding upon them and 
breaking the bonds which hold them together, so that they 
fall to pieces. 

The method which the ferment adopts in separating the 



268 PHYSIOLOGY AND HYGIENE 

compound into its constituents is too complex to be de- 
scribed here. It works in quite a different manner from 
that in which an ax splits a piece of wood ; for the ax 
simply gives us two smaller pieces of the same substance, 
while the ferment gives us two or more new substances. 
But the process is one of splitting up in both cases. And 
when the ferment has split one molecule it still remains to 
split more. It is not used up in the process, as is an acid 
which splits up a salt b}^ chemical combination. Thus, in 
cider in which the sugar has been fermented, the j^ast fer- 
ments can still be found at the bottom of the liquid, ready 
for action upon a new mixture. 

(Unorganized ferments. In addition to these organized 
ferments there is another class of ferments, represented by 
the digestive ferments, ptyalin, pepsin, rennin, and so forth, 
already mentioned, which are simple chemical substances, 
not living organisms. In contradistinction to the organized 
ferments these non-living agents are called unorganized fer- 
ments. They are produced by the activity of gland ceUs, 
just as many organic substances, proteids, sugars, and gly- 
cogen, are produced. Their method of action is similar to 
that of the organized ferments.^) 

In addition to their work in assisting in the decomposi- 
tion of the dead organic matter, these organized ferments 
have another action which makes them of special interest 
to us. They cause certain diseases in men and animals 
known as the infectious (Latin inficere, 'Ho infect, corrupt") 
diseases. These diseases are due to certain of these low 
forms of organisms which lodge in the body and set up 
processes of fermentation there similar to those which are 
set up in the dead organic matter ; and most of them are 
due to the special class of ferment known as the bacteria 

1 The fermentative action of the organized ferments is probably due to an un- 
organized ferment, which is secreted by the ferment organism which is a li\ang cell. 



FERMENTS AND BACTERIA 




(Greek hoMeriou, ''a little staff")- This name was given 
because the first bacteria found were the rod-shaped forms 
known as bacilli. 

Bacteria. Bacteria are minute vegetable organisms, so 
small that the}' can be seen only by the aid of a powerful 
magnifying- lens. You can gain some 
idea of their size from the fact that 
thousands of them could find lodgment 
upon the head of a pin. Some of them 
are shaped like round balls, some like 
little rods, some like spiral threads 
(Experiment 6, p. 275). 

These organisms are alive and grow 
and multiply. Many of them are every- 
where about us, in the air and soil and 
water, and within our own bodies. 
Otliers, like most of those bacteria which 
cause special diseases, as typhoid fever 
or smallpox, are not generally distribu- 
ted, but are found only in regions where 
these diseases have been, or in substances 
which have come from such regions. 

The manner of action of bacteria is that of fermentation, 
described on page 267 and also in Chapter VII. 

When the bacteria act upon the dead plants or dead 
animal tissues lying about on the ground, they break up 
these substances into simpler substances. So also when the 
bacteria of disease enter and effect a lodgment in our bodies, 
they break down our tissues in the same manner. 

Some of the common diseases caused by these bacteria 
acting in this way are diphtheria, consumption, scarlet fever, 
measles, whooping cough, typhoid fever, smallpox, and 
probably influenza. 

In diphtheria (Greek diphtJiera, "parchment" — membranes 




SpirilH 



Bacteria. 



270 PHYSIOLOGY AND HYGIENE 

resembling parchment are formed in the throat in this dis- 
ease), for instance, the httle rod-shaped bacilli which cause 
this disease lodge in the membrane of the pharynx or 
larynx, and feeding upon the body substances, grow and 
multiply. Thus feeding, they irritate and decompose the tis- 
sues and set up inflammation and necrosis (that is, death of 
the tissue cells) therein, so that the membrane of the throat 
becomes swollen and disintegrated. The throat becomes 
very sore, and the passages are often obstructed by the in- 
flammatory products formed. At the same time, in thus 
feeding upon and disintegrating the tissues, the bacteria pro- 
duce or bring about the production of poisonous substances 
(toxines), which are absorbed into the system and make the 
patient very ill with fever, headache, nausea, and other 
symptoms. 

All these processes, the inflammation in the throat and 
the absorption of the poison, may bring about the death of 
the patient. But if he is strong, in time his body will begin 
to produce a substance which offsets the action of the diph- 
theria poison and kills the bacteria in the throat. This 
antidote is called an antitoxine (Greek anti, '^ against," and 
toxikon, " poison"). When this is formed in sufficient amount, 
the patient begins to get well. Often, but not always, the 
power of keeping or forming this antitoxine remains there- 
after with the patient, so that he cannot have diphtheria 
again. This condition is called immunity (Latin niunire, " to 
fortify"). 

Now, out of all this study of diphtheria and the bacteria 
which cause it, some very important results have come. Men 
have learned how to compel these bacteria to produce this 
antitoxine for them in animals, as horses, and so to-day when 
a patient has diphtheria Ave do not have to watch him die in 
spite of our care, or to wait a week or a month until his own 
cells form antitoxine enough to stop his disease, but we can 



FERMENTS AND BACTERIA 271 

put some of this antitoxine which has been prepared from 
horses into him, and cure him within a few days. 

All the infectious diseases are caused in a similar manner 
by their special organisms, and perhaps by studying these 
bacteria we shall be able to compel them to provide antitox- 
ine for us, as we have the diphtheria bacillus, or to produce 
immunity, as we have the cowpox organism.^ But whether 
we obtain this end or not, we have by a study of tlieir habits 
learned a great deal which will help us in preventing (Latin 
prefix jpr^, and venire, "to come"— to come in advance) the 
diseases which they cause. 

Some of the facts concerning the habits of bacteria are of interest 
in connection with some of the common practical customs of o'ur daily 
life. For instance, we find that many bacteria are more active in warm 
temperature than in cold. This fact explains to us why meat is harder 
to keep in summer than in winter, and teaches us the reason for the 
use of ice and refrigerators for keeping milk and meat. 

If the action of ferments is absent, some foods will keep for an in- 
definite period. We find that freezing stops the action of the ferments ; 
therefore we freeze our meat when we wish to keep it for a long time. 
Much of the meat shipped across the ocean is treated in this way. Such 
meat will keep as long as it is frozen. The meat upon a mammoth 
which was found frozen in northern Russia, where the animal had died 
thousands of years ago, was so fresh that the dogs ate it. 

Cooking also kills the bacteria in food and stops all fermentation for 
the time. In canning food the bacteria are first killed by cooking or 
heating the food. The food is then closed in cans, where no new bac- 
teria can get to it, and thus keeps (Experiments 5 and 6, p. 275). 

Most ferments need water for their life and activity. Drying meat 
rapidly will therefore keep it, as the bacteria cannot act without the mois- 
ture. This is a common method of keeping meat in warm countries. 

Making fruit into preserves also keeps it in the same way, as the 
sugary syrup which is formed has depleted the substance of the water. 

Study of bacteria in the infectious diseases. In studying 
these bacteria of disease we find that they pass from the 

1 This is the organism used in vaccination against smallpox. 



272 PHYSIOLOGY AND HYGIENE 

body of the sick person in the excreta : the diphtheria and 
the tnbercnlosis organism in the exudations from the mouth 
and throat and nose, the typhoid organism in the faeces, the 
scarlet fever organism probably in the scales of skin which 
come away. The bacteria which are scattered in these ways 
can live for a long time in the air or soil, float about in dust, 
and then if they happen to get into another person's body 
can cause the same disease there. 

The knowledge of these facts shoidd lead us to be very 
careful of the disposal of excreta and of all materials 
which have been in contact with a sick person. They 
should, if possible, be subjected to some treatment which 
kills the bacteria in them. Such treatment is known as 
disinfection (Latin dis, privative prefix, and inficere, "to cor- 
rupt"— to remove corruption). 

Disinfection. The disinfection of any substance can be 
accomplished in various ways. One method of disinfection 
is burning. This method should be applied to all the cloths 
upon which a patient with phthisis or diphtheria expectorates 
(Latin ex, "from," and ijedus, ''the breast"). Anotlier 
method is steaming or placing in boiling water and boiling 
for twenty minutes. The prolonged high temperature 
kills the bacteria (Experiment 6, p. 275). This method may 
be applied to the clothes and bedding of any person ill 
with an infectious disease. A third method of disinfection is 
washing or mixing Avith chemical substances which kill the 
bacteria. 

Among these substances the most important are corro- 
sive sublimate, carbolic acid, chlorinated lime, formaldehyde 
(formalin), sulphur. These substances are widely used for 
disinfection. Thus, the fecal discharge of a typhoid pa- 
tient should be thoroughly mixed with one ounce of chlori- 
nated lime before being disposed of. Articles from the 
room of the sick person which cannot be boiled or steamed 



FERMENTS AND BACTERIA 273 

may be washed with corrosive sublimate solution (1 part to 
1,0(30) or carbolic acid (1 part to 20). 

The room itself and the furniture in it may be disinfected 
by filling the room for twenty-four hours or more with for- 
maldehyde gas or sulphur funics.^ 

Contagion (Latin contingere, "to affect by contact"). The 
knowledge of the fact that diseases may be carried from 
one person to another by the excreta, by articles which 
have been in contact with the sick person, by people who 
have been with the patient, and by means of the air, 
teaches us to be careful not only in dealing with patients 
suffering from severe infectious diseases, to isolate them 
and disinfect all things in contact with them, but also 
to exert the utmost care in regard to our ordinary hab- 
its of life. People apparently in good health ma}^ have 
disease germs about them which if conveyed to another 
may give the latter disease. The air and soil about us con- 
tain many germs Avhich are capable of causing disease if 
they get a chance to enter the body, as in an open wonnd„ 
It must be our care to diminish as much as possible by good 
habits of hygiene these opportunities for infection. 

We must never take into our mouths any article which 
has been in the mouth of another without first washing it. 
Penholders and pencils in common use in schools should be 
placed in disinfectant solutions after use. 

When we have coughs we must never expectorate upon the 
sidewalk or floor, but into a cloth which can be boiled or burned . 

We must keep clean, for filth is a great breeding ground 
of disease. 

1 Mode of fiimigation (hRtin fumigare, "to smoke") vnth formaldehyde of room 
where a patient lias been ill with an infectious disease : 

Hang np and loosely spread out clothing, bedding, and rugs, leaving chair* and bed- 
stead imcovered. Spray everything thoroughly with water. Close tightly all open- 
ings to the room ; then distill through keyhole five ounces of formaldehyde solution for 
every ten square feet of space, or burn in the room paraform pastils — one sixty-grain 
pastil for every hundred cubic feet of space. 



274 PHYSIOLOGY AND HYGIENE 

Whenever we get an open wound we must wash it care- 
fully. 

Most of all, we must keep ourselves m good health and 
avoid all undue exposure to cold or poisoning or to disease in 
others, for a healthy condition of the body is the first pre- 
ventive of disease. 



STUDY OF ORGANIZED FERMENTS 

YEAST 

1. Add a little baker's yeast to a five per cent solution of grape 
sugar. Place in a wide-mouthed, loosely stoppered bottle, in a temper- 
ature from 70° to 95° F. 

After a few hours take up some of tlie sediment with a pipette, and 
place upon a glass slide. Cover with a cover slip and examine with a 
microscope (three hundred to five hundred diameters). 

Note the yeast cells. 

Note the younger cells budding from the parent cells. 

YEAST FERMENTATION 

2. Observe the changes which occur in the appearance of a mixture 
of yeast and sugar during the day. 

The increased amount of sediment and scum is due in great part to 
the multiplication of yeast cells. 

Note the bubbles rising through th(^ liquid. Tliese are bubbles of 
carbon dioxide gas, formed iu Mie splitting up of the sugar to carbon 
dioxide and alcohol. 

Note the change in the odor of the li(|ui(l. 

3. Pass a U tube through the cork of the bottle, so that the 
end within the bottle lies above the mixture. Place the other end in 
some limewater in a test tube. Note the change which occurs in 
the limewater. This is the same change, due to the same agent, 
which "you have noted iu Experiment 6, page 34, and Experiment 2, 
page 194. 

The alcohol which is formed by the yeast remains in the mixture. It 
can be separated by distillation. 



FERMENTS AND BACTERIA 275 



HABITS OP YEAST— KFFliCT OF COLD UPON ACTIVITY OF CELLS 

4. Add some yeast to a grape-sugar mixture. Place in the ice 
oliest. Observe the mixture from time to time, and compare its condi- 
tion with that of the mixture used in Experiment 1. 

Wliat conclusion can you draw from the result of this experiment? 

5. Place some yeast in a sugar mixture. Boil mixture. Then set 
aside in a warm place, as in Experiment 1. Note results during the 
day as compared with those in Experiment 1. Draw conclusions. 



DEMONSTRATION OF BACTERIA 

6. Boil some finely chopped hay in water for ten minutes (not 
longer). Take a little of the scum which floats upon the surface of the 
cooled mixture upon the end of a glass rod which has previously been 
passed through a flame, and place it upon the surface of an agar slant 
culture. (Agar is a substance which serves as food for bacteria. If • 
some of it is kept in a stoppered test tube it can be used at any time to 
grow the bacteria upon. Get some agar tubes with water of condensa- 
tion present.) Keep the agar tube upon which the hay scum has been 
placed stoppered with cotton in a warm place. The next day a 
white creamy substance will appear upon the surface of the agar. This 
white substance consists of millions of little bacteria which are 
growing rapidly upon the agar. This bacterium is known as the hay 
bacillus, or Bacilhis subtnis. These bacilli are present upon hay and 
collect in tlie scum upon boiling. The few of these contained on the 
end of the rod produce the myriads wliich form the white growth 
upon the agar. 

Take some of the water of condensation from the tube and place 
upon a glass slide, ('over with a cover slip and examine with a high- 
power lens. The bacilli, which look like rods, will be seen. They are 
motile and can be seen to move. 

If some of the white growth or this water of condensation is placed 
upon a second clean agar culture, a similar growth w'ill appear. 

Effect of high temperature upon bacteria. If the culture tube con- 
taining the bacilli is boiled for half an hour and then some of the 
growth is transplanted, the bacilli will fail to grow upon the new tube, 
as they have been killed by the prolonged high temperature. 



276 PHYSIOLOGY AND HYGIENE 



QUESTIONS 

I. Is any form of matter or force in the world ever really lost? What 
becomes of the elements of the matter which makes up the leaves and 
the flowers when these die and decay? What agents bring about this 
disintegration and decay of organic matter? What are bacteria? Are 
they useful? When do these small organisms do harm? Describe their 
growth upon and in the matter of living bodies. 

II. "^Tiat class of diseases do they cause ? How can we protect our- 
selves against these diseases? Is vaccination a good thing? Why? 
What is immunity? What is antitoxinef What is disinfection? 
What is isolation? 



CHAPTER XVI 

DISEASE -ITS PREVENTION AND ITS CARE 

AS we have learned, disease is some disorder of the struc- 
jLJL tnres ov the functions of the body. The causes of these 
disorders are very numerous. 

Disease may arise from some mechanical injury from 
without. Such disorders are fractures and contusions or 
sprains resulting from blows or falls, or open sores result- 
ing from cuts or bullet wounds. 

It may arise from exposure to cold and wet. Such dis- 
orders are colds and inflammation of the throat or of the 
lungs. Exposure of this kind is a very important element 
in the contraction of many diseases of serious nature, as 
pneumonia, sore throat, rheumatism (Greek rhemna, '' a flow- 
ing"— exudation), nephritis (Greek nephros, "kidney"), con- 
sumption (Latin consumere, "to waste away"), influenza 
(grippe). The exposure to cold or damp is often not the real 
cause of these diseases, but it reduces the vitality (Latin vita, 
"life") of the body and its power of resistance, and so gives 
the disease a chance to gain a foothold. Thus, pneumonia is 
caused by a minute live organism belonging to the class of 
bacteria already described. This germ is everywhere about 
us in the air, even in our mouths and throats. While the 
body is in a state of health it cannot gain a foothold in it, 
but the moment the vitality of the body is reduced by cold 

277 



278 PHYSIOLOGY AND HYGIENE 

or some other cause this little enemy may find its chance 
and invade the lungs, causing an inflammation there which 
is called pneumonia {Greek pneumon, '4ung"). 

Animal and vegetable parasites, as the bacteria, are a 
common cause of disease. 

The bacteria of some diseases, like those of pneumonia, 
are everywhere about us in the air and soil. Our only 
method of preventing these diseases is therefore to keep our 
bodies in perfect health, or when some disorder, as a cold or 
a wound, arises in spite of our precautions, to use extra care 
against the invasion of the disease germs. 

Thus, if we receive a cut we can take great care to wash 
it thoroughly and to cover it, so that the germs which may 
be in the air or on objects which we may touch may gain 
no entrance ; or we can even apply to the wounds the sub- 
stances known as antiseptics (Greek antiy " against," and 
sepo, ''putrefy") or disinfectants, which destroy these germs. 

The bacteria of many of these diseases, however, as 
typhoid fever and smallpox, do not live generally in the 
air and soil about us. They get to us only by being 
carried from some other person suffering from the dis- 
ease. The observance of the ordinary rules of hygiene is 
not the sole means of preventing these diseases. We can 
aid in their prevention by keeping away from persons 
suffering from them, or by ourselves keeping away from 
other people if we are suffering from these diseases or have 
been exposed to them ; for the germs of some of these dis- 
eases, as scarlet fever, may be carried from one person to 
another on the clothes of one who has seen the sick person. 

Other general causes of disease are improper feeding, 
overwork, taking insufficient rest, or the taking of sub- 
stances which poison the body, such as alcohol, tobacco, 
opium, decayed meats, or arsenic. These causes themselves 
may give rise to disorder, or they may, like exposure to cold 



DISEASE — ITS PREVENTION AND ITS CARE 270 

and wet, reduce the vitality of the body, and so offer a 
chance for the contraction of infectious or other diseases. 
Thus, people who are overworked or underfed are more apt 
to contract influenza or septicaemia when exposed to it. Al- 
cohol drinkers are more prone to contract diseases of the 
throat and lungs and heart than abstainers. 

GENERAL PRINCIPLES OP PREVENTION OF DISEASE 

The first preventive against all disease is the observance of 
the laws of health. The knowledge of these laws is obtained 
by the study of the body. 

The rules of living which you have learned from this 
study, in brief, are : to eat plenty of good food ; to observe 
regularity in meals, in work, in sleep ; to take plenty of out- 
of-door exercise ; to avoid all substances which can injure 
the body ; to avoid all undue exposure to cold or wet or con- 
ditions of disease. 

The second method of prevention of disease is to stop the 
carrying of disease germs from one person to another. This 
work in great part is the office of the boards of health and 
the physicians of our communities. Physicians and scien- 
tists have been studying for years the nature of diseases 
which are due to these bacterial germs. As a result of the 
knowledge gained by these studies, they are now able to do 
much toward the prevention of many of them. 

The first method which they use is that of isolation. When 
a physician discovers that his patient has scarlet fever or 
diphtheria, he has him separated from other people as much 
as possible, so that the bacteria from his disease may not 
infect any one else. A sign is placed upon the house, to keep 
people from it. The other children of the family are kept 
from school, that they may not carry the disease germs to 
the children in school. 

HEWES, P. & H. — 18 



280 PHYSIOLOGY AND HYGIENE 

Another method which is used to prevent the spread of 
disease is disinfection. This method and tlie means of its 
application have been described in the chapter npon bacteria 
and the infectious diseases. 

A third method of tlie prevention of these diseases is by 
the production of immunity. Thus, people are made immune 
to smallpox by the process known as vaccination (Latin 
vacca, "a cow" — serum fi'om a cow with cowpox is used in 
vaccination). By having all children vaccinated before 
entering school it has been found possible practically to 
stamp out this disease from our communities. 

Children can also be made immune to diphtheria by treat- 
ing them mth the substance known as diphtheria antitoxine. 

It is the duty of each one of us to assist in every way pos- 
sible the boards of health and physicians in the work of 
preventing and restricting disease. 

The following directions for the prcA^ention and restriction 
of dangerous communicable diseases are issued by the Michi- 
gan Board of Health for the use of teachers of that State in 
giving instructions to the children in the schools. 



DANGEROUS COMMUNICABLE DISEASES IN THE ORDER OF 

THEIR IMPORTANCE, MODES BY WHICH THEY ARE 

SPREAD, AND BEST METHODS FOR THEIR 

RESTRICTION AND PREVENTION 

Consumption is now known to be a communicable disease. It is 
spread by the dust of dried sputa, and also by milk and meat of tuber- 
culous animals. The most important measure for the restriction of 
consumption is the disinfection or destruction of all sputa of every 
consumptive person. 

It is best that all persons who have a cough should carry small pieces 
of cloth (each just large enough properly to receive one sputum), and 
paraffined paper envelopes or wrappers in which the cloth, as soon as 
once used, may be put and securely inclosed, and, with its envelope, 
burned on the first opportunity. 



DISEASE — ITS PREVENTION AND ITS CARE 281 

•Pneumonia is spread by a germ whicli is in the sputum of those who 
have the disease (and of some wlio do not have the disease, unless, pos- 
sibly, after exposure to the inhalation of cold air). Care should always 
be taken to destroy or disinfect all sputa of those who have pnemnonia. 

Influenza is now believed to be spread by a germ which finds its way 
from infected handkerchiefs and other articles and places into the nose, 
throat, and air passages of persons susceptible to this disease. The 
measures for its restriction are therefore obvious — isolation and disin- 
fection. 

Diphtlteria is spread by the sputa, saliva, and whatever comes from 
the throat and mouth of the patient, and by the dust which results from 
the drying of such saliva. The germs of diphtheria sometimes remain 
in the throat weeks after apparent complete recovery. For its restriction 
and prevention, isolation and disinfection are the important measures 
—isolation of every infected person and thing, and complete disin- 
fection. 

Typlioid fever. Unlike typhus fever, typhoid fever is not so often 
contracted directly from the sick person, but usually from the dis- 
charges from the bowels and bladder of the sick person. These always 
should be properly disinfected. Undisinfected discharges, if dried and 
formed into dust, may spread the disease through the air. Tlie chief 
soua'ce of danger, however, is believed to be drinking water contami- 
nated by sewage or leachings from privies, etc. The germs permeate 
the entire body of an infected person, and sometimes are found some 
time after apparent recovery. The germs of typhoid fever are not 
always killed by freezing, but are killed by boiling. All suspected 
water should be boiled. 

Scarlet ferer. The germ of scarlet fever is not yet identified ; but 
that there is a germ seems to be proved by the well-known communi- 
cability of the disease from person to person. It is spread by the dis- 
charges from the nose, mouth, and throat, and probably also by the 
minute scales which are thrown off from the surfaces of the body. 
Isolation and disinfection are the measures by which this disease is 
restricted. 

Measles is spread from person to person, directly and indirectly. 
Isolation and disinfection should be enforced. 

Smallpox. Smallpox is a contagious disease ; it spreads by means of 
particles given off from the surfaces of the body. By vaccination and 
revaccination smallpox may be and should be almost wholly prevented. 
One vaccination or once having smallpox does not protect for life. Re- 
vaccination should be had once in about five years, also whenever small- 



282 PHYSIOLOGY AND HYGIENE 

pox is prevalent, and certainly immediately after one has been exposed 
to the disease. 

Cholera is spread in much the same way as is typhoid fever. The 
same precautions recommended to prevent the spreading of typhoid 
fever should be taken as soon as cholera appears or threatens. 

WHAT TO DO UNTIL THE PHYSICIAN COMES 

Everybody should have some general knowledge of the 
care of illness, of wounds and injuries, so that he may 
assist the physician or act in his place in emergencies. 

There are many slight indispositions or injuries for which 
there is no need of sending for a phj- sician. Thus, if a per- 
son has a cold in the head, he can often give it all the care 
it needs by avoiding hot rooms and drafts, by staying in at 
night, going out in the daytime for vigorous exercise, and 
perhaps applying vaseline regularly for a day or two to his 
nostrils. If he has an indigestion he can help it by being 
careful to eat only good mild foods, as milk, soft eggs, toast, 
or well-cooked beef or chicken, for a few days. If lie 
receives a slight cut from a knife, or a bruise from a fall, he 
can care for it himself. 

Even in cases of more severe illness or injury it is almost 
always possible to do something to help the sufferer before 
the physician arrives, if you only know how to set about it. 
In many accidents, such as a lacerated artery or suffocation 
from drowning, it is often necessary to act before the arrival 
of the physician to save tlie life of the patient. 

The instructions for action in these emergencies given 
here are very brief, so that they may be easily carried m 
the memory. 

Cuts and lacerated wounds. Where a cut is made with a 
sharp mstrumeni it bleeds freely. If such a cut is small it 
is sufficient to bind it firmly m a bandage so that the two 
edges of the wound are brought together. Healing will take 



DISEASE — ITS PREVENTION AND ITS CARE 283 

place in a short time. Where the bleeding is not free, or 
where the instrument which made the cut is dirty, it is well 
to wash the wound thoroughly with an antiseptic solution. 
Such a solution may be made by putting a seven-grain tab- 
let of corrosive sublimate into a quart of hot water. All 
lacerated wounds, or tliose made by tin cans, rust}' nails, 
or glass, should be so washed before they are bound up. 
Where the cuts are large or deep, it is frequently necessary 
to stitch together the edges of the wound. When a wound 
heals promptly it leaves no scar. When there is loss of 
tissue, so that the wound has to heal from the bottom upward, 
a scar is left. 

If the wound severs a large blood vessel the bleeding is 
more difficult to control. This is especially tri;e if the ves- 
sel is an artery. You can always tell when the cut vessel 
is an artery by the fact that the blood leaps in spurts from 
the wound and is of a bright-red color. The blood from a 
vein flows in a steady stream and is of darker color. 

Where an artery is bleeding it is necessary to apply some 
pressure to the vessel between the point of injury and the 
heart. Thus, if the cut be in the leg or arm, seize the limb 
high up as firmly as possible in the hands until a large (one- 
half inch) cord or knotted handkerchief can be twisted round 
it. The cord can be made to press very tightly by twisting 
it with a stick. A half-inch soft rubber tube makes the best 
band of this kind. Often it is necessary to place a pad of 
cloth beneath the band over the artery, so as to obtain a 
direct pressure. A physician should be sent for at once in 
all such cases. Where the edges of cuts or wounds are 
much swollen and painful during the period of healing, fre- 
quent applications of hot-water compresses will give much 
relief and hasten resolution. 

A bruise or contusion is an injury to the soft parts of the 
body. Frequently there is escape of blood beneath the skin, 



28J: PHYSIOLOGY AND HYGIENE 

caiising a black-and-blue spot. The best treatment for a 
bruise is frequent applications of very hot compresses. This 
eases the pain and hastens resohition (Latin )'e, " again/' 
and solvere, "to dissolve"— removal or disappearance of dis- 
ease). Bathing in witch-hazel often gives relief. Applica- 
tions of ice or ice-water compresses are sometimes useful 
where there is much inflammation of the tissues. 

Burns ani scalds. These are ver}^ painful and oftentimes 
very serious injuries. Where the burn is due to heat the 
part must be covered with soft linen cloths npon which some 
aseptic soothing ointment, as boracic acid ointment or car- 
bolized vaseline, has been freely spread. Where the skin 
is unbroken, great care shonld be taken to keep it so. In 
such cases the burn may be covered with l)aking soda. 
Cov^er or Innd up the part in such a manner as to avoid 
friction. Where the burn is due to acids, the x)art must be 
washed with an alkaline fluid, as diluted solutions of am- 
monia or soda. If due to alkalis, as lime or potash, wash 
the part in vinegar and water, or dilute acetic acid. 

Fire. When the clothing catches fire, the person should 
be thrown to the ground and enveloped in a rug or coat to 
smother the flames. 

Frostbites. When the ears or nose or toes or fingers arc 
frost-bitten, they should be rubbed in snow or cold water 
until the circulation of the parts is restored. No warm ;ni- 
or warm applications should be allowed to strike the pni-is 
until the sense of feelmg has returned. They should tlicn 
be protected as in cases of burns and bruises. 

Sprains. These injuries are very painful. The joint sliould 
be immersed in very hot water as soon as possible, and ke])t 
there until pain is relieved. The part or limb should after- 
wards be kept m a horizontal position and protected from 
pressure. The injured joint should be carefully massaged 
once or twice a day from the very start. This hastens the 



DISEASE — ITS PREVENTION AND ITS CARE 285 

resolution of the swelling and the cure, for the parts regain 
their tone more quickly under mild use. This active treatment 
is much superior to the old method of keeping the joints im- 
movable in bandages or plaster. By this treatment the use 
of the part may be regained in one or tivo weeks. 

Dislocation. When a joint is dislocated the part should 
be supported until a physician arrives. 

Fracture. When a bone is l)roken the part or limb should 
be bound up in such a manner as to prevent all motion of 
the injured bone, and a physician sent for. If the part be 
supported by splints the patient may be carried to his home 
without danger. If the injury is to the arm, place it in 
a sling after the splints are applied, as the dependent 
position increases the swelling and pain. Barrel staves, 
pasteboard, or even an umbrella or cane may be so bound 
to a limb as to serve for a temporary splint. 

Bleeding from the nose. This is a frequent occurrence. The 
loss of a little blood in this way does no harm to a healthy 
person.- To control the bleeding, the patient should sit up- 
right, breathe quietly through the nose, and avoid blowing it. 
If the bleeding does not soon cease, wrap a cloth dipped in 
cold water about the neck, and hold the nostrils with the 
thumb pressed upward upon the upper lip. It may be nec- 
essary to insert cotton pings into the nostrils. Insufflation 
(Latin m, ''in," and svfflare,'^ to blow up") of powdered 
alum into the deep nostril may hasten matters, but is rarely 
necessary. 

Bleeding from the lungs or stomach is a serious matter. 
If blood is coughed up or vomited the patient should be 
kept perfectly quiet upon the back, and a physician sum- 
moned at once. Ice may be freely eaten, but no other sub- 
stances given by mouth until the physician arrives. Above 
all, no alcoholic liquors, the so-caUed stimulants, should be 
given. 



286 PHYSIOLOGY AND HYGIENE 

Foreign bodies in the throat. Fishbones and particles of 
food sometimes stick in the throat. They may be removed 
by conghing and by slapping the patient on the back, or 
they may be reached from above by forceps. If they canse 
trouble with breathing, immediate aid should be summoned. 
When foreign bodies, as coins, are swallowed, it is best to eat 
plenty of food to surround them and carry them onward. 

Foreign bodies, as buttons or peas, which have been in- 
serted into one nostril by children can often be dislodged 
by closing the other nostril and blowing forcibly into the 
child's mouth. 

Foreign bodies in the ear are often difficult to remove. 
The removal may be accomplished by syringing out the 
canal. If insects get into the ear, they can often be coaxed 
out by holding a light close to the ear. If this fails, a little 
oil or glycerin as hot as can be borne should be dropped 
into the canal, and the head turned to one side to allow it 
to run out again. 

Dog bites. The bite of a healthy dog should be treated 
like any unclean wound, that is, washed with an antiseptic 
solution and dressed. If there is probability that the dc)g is 
mad, active treatment should be at once applied. If the bite 
is in a limb, the limb above the wound should be ligatured. 
The wound should be wiped out thoroughly and the surface 
burned with silver caustic or a red-hot poker. The part is 
then poulticed. Where the case is taken in time the patient 
can escape hydrophobia by being subjected to the Pasteur 
treatment, even though the virus from the dog has entered 
the system. 

Fainting. Fainting is a condition of unconsciousness due 
to disturbance of the circulation following weakness or to 
some sudden emotion or pain. A fainting person must be 
laid flat on the back, with the hips slightly elevated. Give 
plenty of fresh air, loosen the clothing, thi'ow cold water 



DISEASE — ITS PREVENTION AND ITS CARE 287 

upon the face and cliest. The hokling of ammonia (smelling 
salts) to the nose may help revive the patient. 

Fits. Fits are, as a rule, spasms in which the person 
trembles and shakes all over and becomes unconscions. 
They may be a symptom of a disease called epilepsy, or of a 
nerv^ous condition called hysteria. In such cases all that 
you can do, as a rule, is to prevent the patient injuring him- 
self while in a fit. A plug of clotli should be inserted be- 
tween the teeth to prevent biting the tongue. The clothing 
should be loosened. In a short time the patient will come 
out of his own accord. If the trouble is hysteria the patient 
ma}^ not shake, but lie quiet and rigid, with staring eyes. 
This is a cataleptic fit. Such a patient can often be awakened 
by pressure upon the supraorbital nerve just above the eye. 

Convulsions in children are common with many dis- 
orders, as indigestion or worms, or even the swelling and 
pain caused by a new tooth coming through the gums. 
Children suffering from convulsions should be immersed at 
once in a hot bath, and a physician sent for. 

Sunstroke. This condition is due to an abnormal eleva- 
tion of the body temperature as the result of exposure to 
continuous heat. People who are working upon a hot day 
and feel dizziness or nausea, with excessive languor, should 
stop work at once, and seek quiet and cold water, else they 
may suffer a real sunstroke. Where the patient is very hot 
the chief object of the treatment of sunstroke is to reduce 
the temperature. The patient should be stripped and 
packed in ice, or in cloths dipped in ice water. The ice 
and water must be applied for an hour or more, with con- 
stant rubbing of the body. In some cases the patient is 
simply exhausted and the body cold instead of hot. In 
such cases heat has to be applied and hot drinks given. 

Croup. This is a very common affection in infancy and 
childhood. It is an inflammatory condition of the throat, 



288 PHYSIOLOGY AND HYGIENE 

and may be due to several separate causes. The child's 
throat appears to be stopped up, and there is great diffi- 
culty in breathing. In such cases a physician should be 
summoned at once. In the meantime hot compresses should 
be placed about the throat and chest, and a hot mustard 
footbath given. 

Toothache. Insert in the hollow of the tooth a plug of 
cotton wet with carbolic acid or laudanum or oil of cloves. 

Asphyxia. Asphyxia may be due to drowning or smother- 
ing, or to coal gas. The treatment is in general the same. 
If it be a case of drowning, turn the person upon his face and 
allow the water to run from the air passages. Then place 
him on the back with clothing loosened, and begin artificial 
respiration. Hold the tongue well forward. To induce 
artificial respiration, grasp the arms just below the elbows, 
raise them in a line. above the head until they meet, then 
lower them to the sides, pressing in upon the chest walls, as 
you come down, to expel the air. Repeat this movement 
fifteen times a minute, for two hours at least. Respiration 
has been restored after a much longer intervfd. At the 
same time the i)atient must be kept as warm as possible 
with l)lankets and hot- water bottles. As soon as the patient 
begins to breathe, he can be given aromatic spirits of 
ammonia in hot water. 

Poisoning. A poison is any substance whose nature it is 
when taken into the body to injure health or destroy 
life. Many of the snbstanees used about a house, as oxalic 
acid, ammonia, Paris green, Rough on Rats, the brimstone of 
matches, and carbolic acid, are violent poisons. It is not an 
unusual occurrence for a. person to take some one of tliese 
substances, or some medicine which is poisonous in large 
amount, by mistake. In such cases prom})t measures are 
necessary. 

There are two things to do. One is to give the antidote 



DISEASE -ITS PREVENTION AND ITS CARE 289 

of the poison; the other is to get the poison out of the 
body. 

An antidote (Greek anti, ''against/' and dkJouai, ''to 
give ") is a substance which will render the poison inactive 
or offset its effects. Where we know the nature of the 
poison Avhich has been taken, we must give the antidote at 
once, and then set to work to rid the body of the poison. 
Where we do not know the poison, or have not the antidote 
at hand, we must set to work at once to remove the poison 
from the stomach. 

This may be accomplished b}^ gi\dng the patient a table- 
spoonful of mustard in a glass of warm water, or a tea- 
spoonful of ipecac. TJiese mixtures will cause almost im- 
mediate vomiting and expulsion of the poison. A better 
method of emptying the stomach is by the introduction of a 
stomach tube to the organ, and the subsequent siphoning 
out with warm water. 

In cases where the poisoning is due to acids or alkalis, 
no emetics or tubes should be used. 

A list of the common poisons, with their antidotes and the 
method of treatment in cases where they have been intro- 
duced, is here given. 

Acids, nitric, sulphuric, hydrochloric, oxalic. Antidote, 
alkalis. Drink a mixture of soapsuds. Get some magnesia 
or soda, and mixing a tablespoonful with a glass of water, 
drink at once. If no magnesia be handy, use lime or clialk, 
or plaster from the wall. Then drink large amounts of warm 
water. No emetic. 

AlMUs, soda potash, ammonia, lye. Antidote, acids. 
Drink lemon juice or vinegar in solution. Follow wdth olive 
oil or castor or linseed oil, or thick cream. No emetic. 

Arsenic. This is present in Paris green, Rough on Rats, 
Scheele's green, and the medicine known as Fowler's solution. 
Antidote, hvdrated oxide of iron. Give milk and white 



290 PHYSIOLOGY AND HYGIENE 

of egg, and induce vomiting at once. Then give the hy- 
drated oxide of iron, which you can get at the nearest drug- 
gist's. Follow with a solution of salt and water. 

Copper^ blue vitriol, vertigris. Give white of Qg^ and milk. 

Mercury, corrosive sublimate, calomel. Give raw eggs 
and milk. 

Lead^ sugar of lead. Induce vomiting. Give Epsom salts. 

Matches. The heads of matches contain phosphorus. 
Induce vomiting. Give soa.psuds or magnesia or soda in 
vv^ater. Follow with mucilaginous drinks. 

Kerosene. Induce vomiting. Give warm milk. 

Opium {morphine). This is a common drug. Some of 
its preparations are laudanum, paregoric, Dover's powder. 
Diarrhea mixtures and soothing syrups also often contain 
ir. To treat, induce vomiting. Give permanganate of pot- 
ash, one grain for each grain of m()ri)liine taken. Give 
strong coffee, and keep patient awake by all means. 

Carbolic acid. Give milk or white of egg. 

Aconite. Induce vomiting. Aromatic spirits of ammonia. 

Belladonna. Induce vomiting. Strychnine. 

There are several plants which grow alK)ut us which are 
poisonous, such as poisonous mushrooms whicli may be 
taken for the edible varieties, wild ])arsley, and the berry of 
the mountain ash. When these have been taken, vomiting 
should be at once induced. 

S)i(d-e hites are very serious affairs to deal with. Tie a 
handkerchief above the wound if on a limb. Suck the 
wound as strongly as possible, wash it thoroughly, and 
apply some lunar caustic or a red-hot iron to the wound. 

Insect hites. Apply ammonia or spirits of camphor, or 
soda. Cover the wound, if a severe one, lest it become 
infected with bacteria. Apply cold compresses. 

Poison ii'ij. Wlien a person is poisoned with ivy the 
poisoned surface should be thorouglily scrubbed with soap 



DISEASE -ITS PREVENTION AND ITS CARE 291 

and water and covered with a liglit ganze dressing which 
admits the air. Ointments and oils are to be avoided. 

There are some substances which are poisons to some 
people and harmless to others. Thus some people are 
Violently poisoned by certain kinds of shellfish which 
others eat without disorder. 

In the sick room. It is the duty of the strong to minister 
to the sick. When there is an invalid in the house every 
member of the household shares in his care with the phy- 
sician. If we are wise and thoughtful in this ministration 
it may be the fortune of any one of us to aid materially in 
making the illness of some sufferer less irksome and his 
recovery more rapid and sure. 

To fit ourselves for this task the first lesson which we 
must learn is that of cheerfulness and hopefulness. Each 
time that we enter the sick room we must bring courage and 
cheering words. Never before the patient or elsewhere, 
even in the face of the most hopeless conditions, must we 
give way to despondency or grief. Onty those who have 
stood at many bedsides and w^atched many hard battles 
for life can have any idea of the power of courage and 
hope to win through a serious illness. These have saved 
more lives than all the medicines in the world, ten times 
over. They are the shining light which the physician bears 
always before him, and which we too must bear. 

The sick room should be upon the quiet and sunny side 
of the house, if possible. The bed should be so placed that 
the patient shall not be exposed to drafts and that he may 
be reached upon both sides. The temperature of the room 
should be kept between 60° and 70° F. Fresh air should 
be coming in constantly through an open window or ven- 
tilator. 

The furniture of the room should consist of cane chairs 
or lounges, and a light bed of single size with a hair mat- 



292 PHYSIOLOGY AND HYGIENE 

tress. A bare floor, with rugs to deaden the noise, is prefer- 
able to a carpeted floor. 

The odors of the si(?k room should be removed by venti- 
lation, not by burning pastils or sprinkling scents, which 
simply cover one odor with another. In all weather the 
windows should be opened for periods at least, if not all 
the time. 

Care should be observed to have the medicines labeled, 
so that no mistake can be made in their administration. 

If the disease is of an infectious nature all the precau- 
tions detailed in the chapter upon infectious diseases must 
be observed. 



CHAPTER XVII 

PHYSICAL CULTURE 
HOME OR GYMNASIUM EXERCISES— GAMES AND ATHLETICS 

IN view of the great advance in the study of physical 
culture which has come during recent years, and of 
the undoubted improvement in health and physical develop- 
ment of the race which appears to be coming as the result 
of the application of the principles of this training in our 
schools and colleges and association gymnasiums, no book 
of hygiene would be complete without some account of 
these methods of systematic physical training. 

The object of the various systems of physical culture which 
are used in some of our schools and all our large colleges is 
the achievement in each individual of the best possible 
degree of physical culture which is compatible with an even 
development on all sides of life. It is not intended primarily 
to produce trained athletes. That is a special branch of 
training which may follow this primary culture. But it is 
the end of all systems to give to each and all a strength of 
constitution, of frame and muscle and heart and lungs, 
which will fit them for the endurance of the necessary work 
of life, and to i-esist disease. 

At the same time that the strength is developed, the pupil 
gains the poise and grace, the control and coordination of 

293 



294 PHYSIOLOGY AND HYGIENE 

action, which should go with health and strength, also sym- 
metry of form and richness of the skin and the complexion. 

Formerly this development was obtained almost wholly 
through practice in games and athletic sports, or by the 
labor which each special individual's occupation entailed. 
Much of it to-day we obtain from games. There is no better 
way. But in addition to these games a certain amount of 
systematic exercise at home or in school gymnasiums is now 
prescribed. Games were not planned to develop each 
and every muscle in the body. Even when a variety of 
sports, as running, rowing, football, is indulged in, certain 
nniscles and parts of the body are likely not to get their 
full share of development; but in prescribed physical exer- 
cise each and every part can be attended to and have some 
special motion produced for its development. Special exer- 
cise should therefore go hand in liand with outdoor games.^ 

For many these physical exercises sliould precede the 
games. There are children who are not strong enough to 
go into active sports without some physical preparation ; 
but after a period of training by the milder methods they 
become capable of entering them. 

A system of physical development may be followed out 
at home or in some school or gj^mnasium. A mild but very 
efficient system may be followed without the use of any 
apparatus. For progressive development, however, and for 
advanced work, a certain amount of simple apparatus is 
necessar3^ 

A very simple apparatus and one sufficient for all pur- 
poses is found in what is known as the Whitely Exerciser, 
or some apparatus made upon a similar plan. This appa- 

' A strikins: demonstration of the effect of regular physical exercise practiced under 
competent directions is found in the results reported by Dr. Beyer, surgeon in charge 
at Annapolis Naval Academy. From these reports we leai-n that even so fundamental 
a matter as gi-owth of the bones — increase in height — is greatly influenced by regular 
physical training. 



PHYSICAL CULTURE 295 

ratns consists of an elastic cord with handles at each end, 
arranged upon a system of pulleys which can be attached to 
the wall by hooks. One hook is placed at about six feet 
from the floor, the other about six inches. By changing the 
attachments of the two pulleys to the upper or lower hooks 
in turn, the apparatus can be used for exercise of the arms, 
neck, or legs, and can be adjusted to the standing or sitting 
positions. There are several sets of apparatus, graded for 
different strengths. Such an apparatus is desirable, but if 
necessary one can get along with a set of dumb-bells. In- 
dian clubs, a horizontal bar, or a set of parallel bars entail 
rather heavy exercise to begin with. They may be used to 
supplement or follow the primary routine exercises. 

The aim of physical culture is the achievement of even 
development. This entails the selection of sets of exercises 
to develop each part of the body. In the regulation of 
exercise the principle of progression is adhered to. The 
pupil begins with a set of mild exercises and gradually 
works up to the more severe ones. In each period the 
exercise is light at first, growing more vigorous after the 
heart and body are warmed up. 

The time of exercise should not be directly after a meal, 
but may be at any other time. 

The parts of the body which must be exercised in turn are 
the legs, the arms, the neck, the shoulders, the thorax, the 
waist, the back, the abdomen. For each part a special set 
of movements is prescribed. 

In each set of exercises you will find some which are per- 
formed without any apparatus. These represent the mild- 
est forms of exercise. If taken out and grouped together these 
exercises make a good system for home use. These simpler 
exercises may be performed with light dumb-bells if desired. 

It is best to begin with the exercises for the legs. The pupil 
takes the proper standing posture, namely, heels together, 

HEWES, P. & H. — 19 



296 PHYSIOLOGY AND HYGIENE 

toes out at an angle of 90^, knees straight but not stiff, hips 
back, chest expanded, shoulders even and back, arms hang- 
ing at the sides, with palms resting upon the thighs. The 
body weight should rest upon the baUs of the feet, not upon 
the heels. 

Calf muscles : 

1. Raise body from floor on toes thirty or forty times. 

2. Circle foot from thirty to forty times. 

3. Raise foot behind and kick alternately. 

4. Stoop and rise alternately, bending at knees (front thigh muscles). 
With apparatus : 

5. With foot in attachment of apparatus, flex (front leg). 

6. With foot attached, flex thigh (back thigh). 

7. Stand AA-ith side to wall, attach farther foot to exerciser, and 
abduct leg (outer thigh muscles). 

8. In same position, attach to inner leg and adduct (inside thigh 
muscles). 

Arm muscles : 
9. Circle hands at wrist. 

10. Clasp and extend fingers forcibly. 

11. Flex and extend forearms forcibly. 

12. Raise arms extended from sides to side of head. 

13. Circle arms. 

14. Lie face to floor and raise body upon arms extending at elbow. 
With apparatus : 

15. Flex fingers. 

16. Flex forearm. 

17. Extend forearm with fingers extended. Back to wall. 

18. Stand side to wall. Raise arm to side of head. 

19. Stand side to wall. Grasp exerciser with farther hand behind 
and pull outward. 

Nos. 18 and 19 also exercise chest muscles and thorax. 
Back of neck and upper back : 

20. Bend head forward and back forcibly. 

21. Twist neck. 

22. Lie face down, and raise face from floor, keeping chest down. 
With apparatus : 

23. Holding attachment of exerciser behind head, bend head back- 
ward. 



PHYSICAL CULTURE 297 

Shoulders : 

24. Extend arms forcibly, throwing them well back. 
Nos. 18 aud 19, given under arm muscles. 

No. 23, given under back of neck and upper back. 

25. Face wall, palms together. Circle arms backward to utmost with 
exerciser. 

26. Back to wall, one hand over head, one at side grasping exer- 
ciser. Advance together. 

27. Back to wall, arms extended. Flex at slioulder. 
Chest : 

All exercise of arms and shoulder, Nos. 18, 19, 25, 26, 27. 

28. Raise arms at full length from sides to head without or with 
exerciser. 

29. Throw arms forcibly back, keeping straight out from shoulder, 
bring palms together and thus forward and back without, then with, 
exerciser, both facing and with back to wall. 

30. Lie on back on floor. Eaise arms above head with exerciser, 
keeping palms together. 

31. Lie on back. Eaise arms, keeping straight out from body. 
Waist, abdomen, back : 

All full-arm movements, Nos. 18, 19, 24, 25, 26, 27, 28, 29, 30, 31. 

32. Hands on hips. Bend forward and back to limit. 

33. Hands on hips. Bend sidewise to limit. 

34. Twist trunk on hips. 

35. Sit on floor. Drop backward and resume sitting posture. 

36. Lie on back. Raise legs extended over body. 
With apparatus : 

37. Eaise hands from sides, straight out and then to sides of head, 
keeping straight. 

38. Bend forward and back, facing wall. 

39. Eowing posture. Bend back forward and back. 

40. Lie on back. Eaise arms straight over head, bring over face 
to sides. 

In addition to the above exercises, certain breathing exer- 
cises with the use of the voice may be practiced under direc- 
tion. At schools, also, exercises in drill are desirable, since 
they teach proper methods of standing and walking, and re- 
quire strict attention in regard to the performance of each 
separate movement. 



298 PHYSIOLOGY AND HYGIENE 

Where special defects exist, as round shoulders, high 
shoulders, a weak waist or abdomen, special exercises are to 
be taken. These must be prescribed by competent directors. 

Before taking up a course of home exercise, one should be 
examined by some competent person, and obtain directions 
in regard to the time which he should employ in exercise, 
the weights which he should use, etc. If a boy begin with 
too heavy exercise he may injure himself. 

At the end of a period of exercise the pupil may take a 
run or a row, or, after cooling off, a swim. 

In regard to the other matters concerning physical culture, 
the proper food, the observance of regular habits, the general 
directions upon these subjects which are given in the chap- 
ters on hygiene of the various organs are to be followed out. 

GAMES AND ATHLETICS 

In certain ways the best methods of exercise are found m 
the out-of-door games of childhood and youth. 

These games are entered into as a pleasure, not as a task. 
There can be no question that more benefit is derived from 
exercise or labor of any kind in which the interest and pleas- 
ure form a constant spur to endeavor, and the mind works 
in harmon}" with the muscles. 

Almost all of these games entail a certain amount of 
mental, together with phj'-sical, exercise. They teach quick 
and decisive action, systematic or combined action (team 
play), in which the individual learns to use liis strength in 
harmony with that of his fellows for the attainment of a 
common end. They teach discipline, forethought, self-con- 
trol, the husbanding of one's forces until the proper time for 
action. They should teach also forbearance, moderation, and 
even self-sacrifice. 

The exercise and training consequent to these games, the 



PHYSICAL CULTURE 299 

open-air life and regular habits, bring about a splendid 
general development of the muscular system, the heart, 
lungs, and vital organs. They give the soundest kind of con- 
stitutional strength. In this latter regard they are, if care- 
fully controlled and regulated (not carried to excess), more 
efficient than gymnasium exercises. Lastly, the participa- 
tion in these games develops a fine ambition for excellence 
in physical manhood or womanhood. 

To serve their purpose, however, these games must be care- 
fully regulated. There must be no excess. The incentive 
to excess which competition gives must be offset by the 
watchful discipline of the supervisor or trainer. All boys 
who participate should first undergo medical examination. 

Those whom physical disabilities make unfit should be 
developed by methods more susceptible to absolute reg- 
ulation. 

The moral side of the sport should be kept at the highest 
level. The men should go in to win, but by fair means 
only. Everything should be in a friendly spirit and above- 
board. All elements of trickiness, of brutality, of hard feel- 
ing, should be eliminated. 

The glory of physical effort and the pleasure of the sport, 
not the desire to win, should be the chief incentives to par- 
ticipation and to play. 

Finally, the athletic interest should be but a part of the 
general interest in the development. The ideal of physical 
culture should go side by side with that of mental and moral 
culture. One part of each twenty-four hours should be de- 
voted to study, one to athletics, one to social intercourse, 
one to sleep. The athletics should be taken as a pleasure? 
not as a task. The desire for the outlet of physical energy 
pent up during the pursuit of other interests should carry 
men out unbidden. 

The tendency of our modern methods in athletics has 



300 PHYSIOLOGY AND HYGIENE 

been, in part away from these best ideals of sport. Espe- 
cially in our college systems, athletics has become too much an 
end instead of a means. Some men go to college to become 
famous as athletes, not to get a full and even development. 
Study and the other interests of life are neglected. The 
systems of training entailed by the serious competitions are 
excessive. Men take special summer training before the col- 
lege year begins. The work becomes a task rather than a 
pleasure. The desire to win leads to the employment of 
unsportsmanlike methods. The intense feeling leads to bru- 
tality. The contests become battles rather than friendly 
competitions. 

The system turns out good athletes and well-developed 
men. It leads to greater excellence from the one point in 
view, the athletic standpoint. But it injures and, to a cer- 
tain extent, disables for life a certain number who partici- 
pate. It inculcates a one-sided ideal, an incorrect sense of 
proportion. The physical harm which results is not a ne- 
cessity of the sport. It is due to the improper regulation of 
it. The blame for this improper method lies partly, as we 
have already hinted, with public opinion at the colleges. 
The exactions of competition, and the sacrifices which are 
required to uphold college honor or attain athletic fame, are 
excessive. But the blame lies also in great part in the ab- 
solutely incorrect and inefficient methods of medical super- 
vision employed in our college athletics. 

The subject of the training of athletes is not established 
upon a scientific basis. It ought to be worked out from a 
physiological as well as from an empirical standpoint. The 
medical directors of college athletics, as a rule, are medical 
men chosen' because they have been themselves athletes. 
They are apt to be men of surgical training whose knowl- 
edge of physiology and internal medicine is limited. 
There should be associated with these men physiologists 



PHYSICAL CULTURE 301 

who could work out the scientific physiological side of train- 
ing at the same time that the trainer is working out the 
empirical side. If this were done we could in the end per- 
haps gJiin some accurate knowledge in regard to the proper 
time and strength (labor) limits of athletic contests, and be 
able to tell in advance, by examination, what men are capable 
of standing a certain amount of training and labor in contest 
without detriment, and what men are not. At present the 
system is very much one of the survival of the fittest. 

Happily this matter of the proper regulation of athletics 
is now receiving the attention it deserves in some of the col- 
leges, and there is a marked improvement in the methods of 
training and in the manner of conducting the contests. 



GLOSSARY 

Special terms are explained in the context, and can be looked np 
through the Index. Only such terms are explained in the Glossary as 
have a general meaning or have more than one meaning. 

Abdominal cavity, the large cavity of the mammalian body lying 
below the diaphragm, which contains the liver, stomach, and intes- 
tines, spleen, and several other organs. It is continuous below with 
the pelvic cavity. 

Abduction, the removal of anything from a substance or body; the 
motion of drawing a limb or pai't away from the midline of the body. 

Absorption, the process of taking up nutritive or waste products by 
the cells or tissues of the body. 

Accumulation, the storing up of substances. 

Adduction, the motion of drawing a limb or part toward the midline 
of the body. 

Afferent, a term applied to anything traveling or conducting from the 
periphery (surface) of the body to the interior or to the central 
organs : afferent impulses, afferent vessels, afferent nerves. 

Albumen, or Albumin, a special kind of proteid substance contained 
in food and in the body tissues. 

Amoeboid motion. The amoeba is an animal consisting of a single cell 
which has the power of changing its form and of moving about in 
water by protrusions and withdrawals of its substance. Any living 
cell which performs similar motions is said to have the property of 
amoeboid motion. 

Antiseptic (Latin «»fi, "against," and sejjsis, "poison"), inhibiting the 
action of a poison. The term is applied specially to substances 
which inhibit the action of bacteria or other organized ferments. 

Apparatus, a device, usually a mechanical one, for the accomplish- 
ment of some function or some special aim. 

Appendage (Latin ad, "to," and pewc?eo, "I hang"), any part attached 
to a central body or part. 

303 



304 GLOSSARY 

Areolas (Latin dim. of area, ''a small space"), a term applied to con- 
nective tissue so constructed as to contain many spaces. 

Articulate, to join in a joint. 

Articulation (Latin artimdo, "1 form a joint "), a joint. 

Articulatory surfaces, surfaces of bones Avhich enter into the forma- 
tion of a joint. 

Assimilation (Latin «<^/, "to,^' and si miUs, "like"), tlie conversion of 
food substances into living tissue. 

Bladder (Saxon hleddra, "a bladder"), a bag or sac serving as a recep- 
tacle of a secreted fluid. 

Canal (Latin canaUs), a tube or passage through which a substance 
may flow. 

Cardiac, pertaining to the heart. 

Catarrh, an inflammatory condition of a membrane, usually attended 
Avith an increased secretion of the cells of the membrane. 

Chemistry, the study of the force by which matter becomes perma- 
nently altered in its properties ; that is, the science of the compo- 
sition of matter and of the changes which it undergoes in this 
composition. 

The chemistry of muscle, for example, is the study of its compo- 
sition and of the changes which occur in the substances which com- 
pose muscle in the processes of metabolism. 

Composition. The composition of a substance is its make-up. As ordi- 
narily used the term means the client iad make-up. Thus, water is 
composed of hydrogen and oxygen. The statement, "milk is com- 
posed of proteids, carbohydrate fat, and mineral substances," refers 
also to the chemical comjyosition, though not to the ultimate compo- 
sition, as in the statement in regard to water. 

We sometimes use the term in a physical sense. Thus, skin is 
said to be composed of epithelial tissue and connective tissue. 

Compress, a pad or bandage applied directly to an injury to com- 
press it. 

Concentrated. A substance, as, for example, the urine, is said to be 
concentrated when its density is greater than normal. 

Congestion (Latin con, "together," and gei'o, "I bring"), an abnormal 
accumulation of blood in a part. 

Constipation (Latin con, "together," and stijm, "I crowd"), retardation 
or sluggishness of the actions of the intestine, causing accumulation 
of the ffeces in the body. 

Constituent, any substance which enters into the composition or 
structure of a greater whole. 



GLOSSARY 305 

Consumption, a disease of the lungs due to the bacterium known as 

the tubercle bacillus. 
Contraction (Latin co)i, "together," and traho, " I draw "), the drawing 

together of any substance, as protoplasm, or any body, as a muscle. 
Decomposition, the breaking up of a substance into its constituents 

(its chemical constituents). 
Degeneration (Latin dcgcuerarc, "to deteriorate"), a change in an 

organism or structure which makes it less tit to perform its function 

or fulfill its usefulness. 
Density. The density of a substance is its comparative bulk as com- 
pared with an equal weight of some standard substance. Thus, in 

Experiment 16, page 126, the white of egg is of greater density than 

the water, a given weight of the former being of less bulk than an 

equal weight of water. 
Detritus, structural material cast off by the tissues or unused portions 

of food, which make up the excreta of the body. 
Dextrin, a carbohydrate substance formed by the digestion of starch. 
Diffusion, the flowing apart or separation of substances into other 

media. 
Digestion, the breaking apart of the constituents of a substance ; a 

term usually confined to the breaking up of food in the alimentary 

canal of the body. 
Dissection (Latin clis, "apart," and seco, "1 cut"), the cutting up of a 

plant or animal for purposes of studying its structure. 
Duct (Latin duco, "1 lead"), a tube which carries substances away 

from organs, usually from glands. 
Efferent, a term applied to anything traveling or conducting from the 

interior or center of the body to the periphery. 
Elastic, possessing the property of stretching, under strain, and return- 
ing to its natural condition when the strain is relaxed. 
Elimination (Latin e, "out of," and limeu, 'threshold"), the expulsion 

or passing out of substances, especially waste substances. 
Emetic (Greek eweo, "I vomit"), a medicine used to produce vomiting. 
Emulsion (Latin cinuJgere, " to milk "), a fat suspended in a liquid in a 

very finely divided condition. 
Epidemic, the prevalence of a large number of cases of a disease in a 

community. 
Equilibrium, balance. The equilibrium of the nutrition of the body 

is maintained when the supply of food and the expenditure of tissue 

balance each other. 
Excreta, the refuse which is passed from the body in any way. 



306 GLOSSARY 

Experiment, a trial ; the operation of subjecting objects or sub- 
stances to certain conditions and observing the results, to test some 
principle or supposition, or to discover some fact. 

Fumigation (LRtin fumigare, "to smoke")? the use of the fumes of a 
substance to disinfect. 

Fuse, to reduce a solid substance to a liquid form. 

Gastric (Greek gaster, "stomach "), pertaining to the stomach. 

Germ (Latin f/erntoi, "a sprout "), a term applied to organized ferments 
as first causes of disease. 

Germicidal, the power of killing germs (organized ferments). 

Glycogen, a carbohydrate substance produced in the liver ; also stored 
up in the muscles. 

Gram, the unit of the metric system of \Yeights. It is equivalent to 
15.43 grains troy. 

Granule, a small particle of material. • 

Gymnasium (Greek fjumnazo/' I exercise "), an establishment fitted for 
conducting muscular exercises. 

Hepatic, pertaining to the liver. 

Heredity, the tendency of the protoplasm of one individual to possess 
the inherent characteristics of that of its ancestors. 

Homogeneous (Greek homos, "the same," and geuos, "kind"), a sub- 
stance of uniform composition or appearance. 

Hydrogen, a gaseous element which enters into the composition of 
many substances. 

Hydrophobia (Greek hudor, "water," and 7)/<o&os, "fea.r"), a disease 
occurring in animals, especially dogs, which may be transmitted to 
man and otlier animals by the bite of the affected animals. 

Idiosyncrasy, a characteristic peculiar to a special individual as dis- 
tinct from the majority of individuals. 

Indestructibility of matter. This term refers to the fact that, in all 
the chan<i:<>s which matter may undergo, none of the matter is ever 
lost. 

Infectious disease, a disease due to some organism obtaining settle- 
ment in the bod\\ 

Inflammation (Latin i», and flamuw, "I flame"), a pathological (dis- 
eased) condition of a tissue, usually manifesting itself by redness and 
swelling of the part. 

Intelligence, the power of reasoning and of understanding the rela- 
tions of things. 

Lens, a piece of a transparent substance so arranged as to converge or 
disperse the rays of light. 



GLOSSARY 307 

Liberation, setting free. 

Locomotion, the property or act of moving about from place to place 
by one's own action. 

Membrane, a cellular layer of tissue used to cover the surface of some 
part of the body. 

Microbe (Greek w/Atos, "little," and bios, "life"), a microscopic or- 
ganism, as a bacterium. 

Mixture, a physical combination of tv/o substances. 

Molecule, the smallest quantity into which the mass of any suostance 
can be physically divided, or in which any substance can exist in a 
free state. Thus, a molecule of sugar is the smallest particle of 
sugar which can exist. This molecule may be broken into smaller 
parts called atoms, but these atoms are not sugar, but portions of 
the elementary substances which are built up together to make the 
sugar molecule. 

Motor (Latin moveo, "1 move"), a term applied to nerves which con- 
duct impulses which produce motion in a part. 

Nostril (Anglo-Saxon nosn, " nose," and thyrl, " a hole "), one of the two 
outer openings of the nose. 

Nutrition (Latin nutrio, "1 nourish"), the process of the nourishment 
of the body and its parts. The term is also used to describe the con- 
dition of the body; thus, *^the nutrition of the body is good," 
meaning that the body is well nourished. 

Olfactory (Latin oJfacio, "1 smell"), pertaining to the sense of 
smell. 

Optic (Greek opsis, "sight"), pertaining to the sense of sight. 

Organism, a term applied to any individual entity having the property 
of a separate life, as an animal body, a plant, or a bacterium. 

Ossification, the transformation of any living substance, as, for ex- 
ample, cartilage, to bone. 

Paralysis (Greek 2Mr«7<^o, ^^I loosen, disable"), the loss of function- 
usually applied to a loss of muscular power. 

Parasite, an organism which lives upon another plant or animal. 

Periphery, the external part or surface. 

Process (LoXin procedo, "I go forth"), a projection of substance; also 
a method or manner of action by which some end is fulfilled. 

Rudimentary. A rudimentary structure is one incomplete in its 
make-up or function, the vestige of some structure useful iii the 
economy of the bodies of some ancestral race. 

Shock. The term is used here to describe any impression or impulse of 
a disturbing nature received by any sensitive object or structure. 



308 GLOSSARY 

Slant culture, a preparation of some nutrient media for some organism, 
arranged with an oblique or slanting surface. 

Stimulation, increase of vital activity. 

Structure. The structure of a body means its building plan. We speak 
of a muscle as a structure, meaning a thing built up by the physical 
association of several parts. 

Suspension. A substance is said to be in suspension when its physical 
j)articles are maintained floating throughout a liquid. 

System, a combination of structures and organs for the accomplish- 
ment of a definite purpose. 

Systemic, belonging to the whole body. 

Transformation, change of nature or form. 

Translucent, alloAving light to pass through. 

Utilization, the making use of. 

Vessel, a structure which carries materials not a part of itself. In 
physiology the term is applied to tubes which carry the food and 
waste substances to and from the tissues, as the blood vessels, the 
lymph vessels. 

Viscera, a term applied to the internal organs. 

Vital, endowed with life, or pertaining to living things. 

Volition, the power of choice ; will. 

Water of condensation, the water which collects upon cooling. 



INDEX 



Abdominal cavity, 50. 

Abduction, 52. 

Abduction of heat, by evaporation, 
203 ; in respiration, 188. 

Abscess of ear, 258. 

Absorption, 92, 112, 113; physical 
process of, 127 ; by osmosis, 120, 
126 ; of salt, 126 ; of su^^ar, 126 ; 
of water, 103 ; the villi in, 113. 

Accommodation, 248, 259. 

Achilles, tendon of, 73. 

Acid, 121 ; in gastric juice, 111, 
121; reaction, 121. 

Acids, poisoning by, 289. 

Adduction, 52. 

Adenoids, 193. 

Afferent nerves, 216. 

Agar culture, 275. 

Air, 179 ; expired, 187 ; inspired, 
186 ; temperature of expired, 
188 ; temperature of inspired, 
188 ; volume of expired, 188 ; 
volume of inspired, 188. 

Air passages, 180. 

Air pressure, 185, 

Albumin, egg, 127 ; in blood, 117 ; 
of food. 111, 116. 

Albumose, 111. 

Alcohol, 143 ; action of, in body, 
149-151; distillation of, 147; 
poisonous action of, 148 ; source 
of, 143; value of, as food, 151. 

Alcohol drinking, effects of, upon 
the body temperature, 211 ; upon 
the bones, 60, 61 ; upon the diges- 
tion and digestive organs, 107 ; 
upon the heart and blood vessels, 
174, 175 ; upon muscular work, 
79, 80 ; upon the nervous sys- 
tem, 231 ; upon the respiratory 



system, 190 ; upon the vital func- 
tions, 150. 
Alcohol habit, 152, 231, 232. 
Alcoholic beverages, 145-149. 
Alcoholic (vinous) fermentation, 

144-149 ; use of, by man, 145. 
Alimentary tract (canal), 93. 
Alkaline reaction, 121 ; of saliva, 

110. 
Alkalis, 121 ; in pancreatic juice. 

128 ; poisoning by, 289. 
Alveolus, 181. 
Amoeba, 92. 

Amoeboid motion, 17, 116, 129. 
Amylopsin, 112. 
Anabolism, 30. 
Antemia, 173. 
Anatomy, 14. 
Aneurism, 175. 
Ankle, 46. 

Anterior nerve roots, 218. 
Antidote (of poisons), 288, 289. 
Antipyrine, 238. 
Antiseptics, 272, 278. 
Antitoxine, 270, 280. 
Aorta, 162 ; abdominal, 163 ; arch 

of, 162 ; thoracic, 162. 
Apex of heart, 155. 
Apparatus, for illustrating action 

of muscles and joints, 85 ; for 

exercise, 294. 
Aqueous humor, 245. 
Arachnoid membrane, 223 
Arch of aorta, 162. 
Arm, 45. 

Arterial, blood, 119 ; system, 162. 
Arteries, 118 ; elastic tissue in, 162 ; 

muscle in, 162; named, 162-165; 

structure of, 161, 162. 
Articular surfaces of bone, 57. 



309 



310 



INDEX 



Artificial respiration, 194, 288. 

Arytenoid cartilage, 261. 

Aseptic, 284. 

Ash, 123 ; of milk, 124. 

Asphyxia, 194, 288. 

Assimilation, 115. 

Atheroma, 175. 

Athletics, 298, 299; training in, 

300. 
Atlas, 41.- 

Atmospheric pressure, 185. 
Atoms, 20, 266. 
Auditory, canal, 254; ei)itholium, 

256. 
Auricles of heart, 155, 156. 
Automatic, action, 103 ; acts, 224. 
Automatic regulation of blood 

supply, 169. 
Axis, 41. 

Axis cylinder, 217. 
Azygos vein, 163. 

Bacilli, 269. 

Bacillus suhtilis (hay bacillus), 275. 

Bacteria, 111, 147,' 267, 269, 275; 
agents of decomposition, 267; 
and infectious diseases, 268, 270 ; 
as causes of disease, 268, 278 ; 
habits of, 271 ; methods of de- 
struction of (disinfection), 271, 
285 ; of diphtheria, 270 ; of pneu- 
monia, 277 ; of typhoid, 208, 278 ; 
uses of, in nature, 267, 268. 

Ball and socket joint, 52. 

Bathing, 83, 205. 

Baths, 205. 

Beans, as food, 134, 140. 

Beef, 140. 

Beer, 146. 

Beverages, 141. 

Biceps, 67, 73, 78. 

Bicuspid teeth, 95, 96. 

Bicycling, 83. 

Bile, 101, 102, 114; duct, 102. 

Biuret test for proteids, 122. 

Black-and-blue spot, 284. 

Bladder, 200. 

Bladder, gall, 102. 

Bleeding, 282 ; arterial, 283 ; coag- 
ulation and, 117 ; from lung, 285 ; 
from stomach, 285. 



Blind spot, 248. 

Blood, 115, 128, 129; arterial, 119; 
carbohydrates of, 129 ; circula- 
tion of, 117 ; coagulation of, 116 ;' 
corpuscles, 115, 129, 177; defi- 
brinated, 129 ; germicidal power 
of, 173; plaques, 115, 116; plas- 
ma, 115; pressure, 168; prooeids 
of, 117; salts of, 117; serum, 
117 ; tests for constituents of, 
129 ; venous, 119 ; vessels, 161. 

Body, the, a machine, 10 ; food 
and the heat production in, 211 ; 
structure and parts of, 13. 

Body heat, 28, 29, 209 ; source of, 
210. 

Bone, composition of, 53, 54, 62 ; 
structure of, 54, 57, 61. 

Bone cells, 56. 

Bones, 13, 37 ; flat, 53 ; forms of, 
53 ; irregular, 53 ; long, 53 ; num- 
ber of, 38 ; short, 53. 

Bowels, regulation of, 206. 

Brain, 14, 215, 216, 220. 

Brandy, 148. 

Bread, 147 ; digestion of, 110. 

Breathing. See licdpi ration. 

Bronchi, 181. 

Bronchitis, 171. 

Bruise, 283. 

Burns, 284. 

Butter, 133, 140. 

Cabbage, 134. 

Calcium, 21. 

Calf of leg, 73. 

Calories, 138-140. 

Canalicnli, 56. 

Cane sugar, 112. 

Canine, 95, 96. 

Capillaries, 118, 119, 160, 161, 163; 

in frog, 177. 
Capsule, of joint, 51 ; of kidney, 

199. 
Carbohydrates, 21, 89; digestion 

of, 112; tests for, 123. 
Carbolic acid, as a disinfectant, 

272 ; poisoning by, 290. 
Carbon, in body, 20, 90; in food, 

27, 90, 91. 
Carbonate of lime in bone, 62. 



INDEX 



311 



Carboncates, 21 ; in Wood, 117 ; tests 
for, 02. 

Carbon dioxide, 35; as index of 
impurity of air, 191 ; exchange 
of, in res])irntion, 1S6, 1H7; ex- 
cretion of, 1S7; formation of, 
in ak'oliolic fcrmentalion, 144; 
formation of, in boilv, 197; in 
blood, 187. 

Cardiac orifice of stomach, 99. 

Carnivora, 109. 

Carpal bones, 45. 

Cartilage, 37 ; costal, 43 ; in bron- 
chi, 182; in trachea, 182; of 
hxrynx, 261 ; of thoracic wall, 43 ; 
ossification of, 58 ; upon articu- 
lar surfaces, 5G, 57, 61 ; structure 
of, 57. 

Casein, 89, 111. 

Cell, the, 17. 

Cell activity, 18; processes, 15. 

Cells, 15, 16, 22 ; as unit of struc- 
ture, 15, 16; blood, 116; bone, 
56; division of, 18; ganglion, 
217; parts of, 17; properties of, 
17 ; varieties of, 17. 

Cellulose, 90. 

Cement, 95. 

Cereals as food, 134. 

Cerebellum, 220. 

Cerebral hemisjdieres, 220. 

Cerebro-spiiial fluid, 223. 

Cerebrum, 220. 

Cervical vertebra?, 41. 

Cheese, 133. 

Chemical composition, of body, 19 ; 
of matter, 20, 265. 

Chewing gum, 109. 

Chloral, 238. 

Chloride of sodium, 21, 117. 

Chlorinated lime, 272. 

Chlorine, 21. 

Chocolate, 135, 141. 

Cholera, 282. 

Chorda? tendinea\ 156. 

Choroid coat, 245. 

Chyle, 113. 166. 

Chyme, 102, 112. 

Cider, 145, 146. 

Cilia, 182. 

Ciliary processes, 246. 

HEWES, p. & H.— 20 



Circulation, in lymphatics, 166; in 
vessels, 168; of blood, 117, 154; 
portal, 163; i)ulnu)nary, 165; va- 
somotor regulation of, 169. 

Circulatory system, 118, 154. 

Circumvallate papillas, 242. 

Clavicle, 44. 

Clot, 117, 128. 

Clothing, 59, 83, 206. 

Cloves, 141. 

Coagulation, of blood, 116, 128; of 
milk. 111. 

Cocaine, 238. 

Coccyx, 41. 

Cochlea, 256. 

Cocoa, 135, 1*1. 

Codeine, 237. 

Coffee, 142. 

Cold, taking, 171. 

Collar bone, 44. 

Combustion, 29; evidences of, 34; 
in muscle, (58. 

Compound, a chemical, 20. 

Condiments, 141. 

Cones, 246. ' 

Congestion, 171. 

Conjunctiva, 244. 

Connective tissue, 16, 58. 

Conscience, habit of, 227. 

Consonants, 263. 

Constipation, 207. 

Consumption, 269, 277, 280. 

Contagion, 273. 

Contraction of muscle, 65, 74. 

Contusion, 283. • 

Convolution, 221. 

Convulsions, 287. 

Cooking, 105. 

Cord, spinal, 215-217. 

Cords, vocal, 261, 262. 

Corium, 201. 

Corn, 134, 140. 

Cornea, 245. 

Coronary arteries, 158. 

Corpus callosum, 221. 

Corpuscles, of blood, 115; tactile, 
240. 

Correlation of energy, 29. 

Corrosive sul^limate, 272. 

Cortex, of brain, 221; of kidney, 
198. 



312 



INDEX 



Corti, organ of, 256. 

Coryza, 171. 

Costal cartilage, 43. 

Coughs, 190. 

Cranial nerves, 222. 

Cranium, 47. 

Cream, 133. 

Cricoid cartilage, 261. 

Croup, 287. 

Crown, of head, 49; ot teeth, 95. 

Crura cerebri, 220. 

Crypts of Lieberkiihn, 100. 

Crystalline lens, 246. 

Culture, mental, 227 ; physical, 

293. 
Culture (nutrient media), 275. 
Cuticle, 200. 
Cuts, 282. 

Death, 24. 

Decomposition, 144, 267. 

Decussation. 221. 

Defibrinate, 129. 

Deformity, 61. 

Deglutition, 98. 

Deltoid, 73. 

Dentals, 263. 

Dentine, 95. 

Dermis, 201. 

Dextrose, 112. 

Diabetes, 106. 

Dialysis, 126, 127. 

Diaphragm, 50, 184. 

Diastole, 159. 

Diet, 138. 

Diffusion, 127. 

Digestion, 92; gastric, 111, 125; in 
intestine. 111, 112, 128; in 
mouth, 110; in stomach, 111, 
125; of carbohydrates, 110, 112, 
124; of fats, 112, 125, 128; of 
starch, 124; of sugar, 112; pan- 
creatic, 112, 128; salivary, 110, 
124, 125. 

Digestiv^e ferments, 111, 124. 

Diphtheria, 269, 270, 281; anti- 
toxine, 270 ; bacillus of, 270. 

Disease, 33, 277 ; care of, 282-292 ; 
causes of, 277-279 ; prevention 
of, 279-282. 

Diseases, infectious, 208, 271, 280 



208, 272 ; of room, 273 ; of wound, 
274, 283. 

Dislocation, 60, 285. 

Disposal of excreta, 207, 272. 

Distillation, 147. 

Distilled liquors, 147. 

Dog bites, 286. 

Dorsal, cavity, 50 ; vertebrEe^ 38. 

Dress (clothing), 206. 

Drowning, 194, 288. 

Drugs, use of, 137, 207, 238. 

Drum of ear, 254. 

Duct, bile, 102 ; hepatic, 102 ; tho- 
racic, 166. 

Duodenum, 112. 

Dura mater, 223. 

Ear, 254, 255. 

Education, 227. 

Efferent nerves, 216. 

Egesta, 204. 

Eggs, 37 ; as food, 133. 

Elastic tissue, in arteries, 162 ; in 

'lungs, 182. 
Elbow, 53. 
Element, 20, 265. 
Emotions, 229. 
Emulsion, 112, 126, 128. 
Enamel, 95. 
Endocardium, 158, 161. 
Endolvmph, 256. 
Endothelium, 158, 161. 
Energy, 10, 25, 26 ; as heat, 26, 29 ; 

as work, 26, 29 ; correlation of, 

27; dynamic, 87; in food, 27; 

latent, 87 ; source of, 26 ; use of, 

in body, 28. 
Epidermis, 200. 
Epiglottis, 98, 180. 
Epilepsy, 287. 
Epithelial cells, 16 ; action of, in 

absorption, 113; of glands, 94; 

of mucous membrane, 93 ; of 

venal tubules, 199, 200. 
Epithelial tissue, 16. 
Esophagus, 93, 98. 
Ethmoid bone, 48. 
Eustachian tube, 255. 
Excreta, 207 ; disinfection of, in 

infectious diseases, 208, 272. 



INDEX 



813 



Excretion, 197, 200 ; by intestines, 
204 ; by kidnov, 198 ; by lungs, 
187, 188, 198 f by skin,"200; of 
carbon dioxide, 187 ; of nitrogen, 
197 ; of urea, 197, 200 ; of water, 
188. 

Excretory organs, 197. 

Exercise, mental, 226 ; muscular, 
79. 

Exercises, physical, 293-297. 

Expiration, 186. 

Exposure, a cause of disease, 277. 

Extension, 53. 

Extensors of hand, 67. 

External rectus, 244. 

Eveball, 243 ; motions of, 244 ; mus- 
'cles of, 244. 

Eyelashes, 244. 

Eyelids, 243 ; muscles of, 244. 

Face, 48. 

FfBces, 103, 204, 207. 

Fainting, 172, 286. 

Fang, 95. 

Fascia, 73. 

Fasciculi, 73. 

Fat, 21, 90, 123, 128; absorption 
of, 113 ; as food, 136, 211 ; diges- 
tion of, 112, 126, 128; emulsion 
of, 112, 126, 128 ; energy in, 211 ; 
in blood, 117 ; in milk, 124 ; tests 
for, 123. 

Fatigue, muscular, 82. 

Fatty acid, 112. 

Fauces, 97. 

Fehliug's test, 123. 

Femur, 46. 

Fenestra, ovalis, 255 ; rotunda, 255. 

Ferment, fibrin, 117. 

Fermentation, 144, 267, 274 ; alco- 
holic (vinous), 144-149 ; as cause 
of disease, 268 ; in body, 111 ; in 
mouth, 104 ; use in nature, 267. 

Ferments, 111, 144, 267; digestive, 
111; effect of cooking upon, 271, 
275 ; effect of freezing upon, 271, 
275; organized. 111, 267; unor- 
ganized, 111, 268. 

Fever, 270. 

Fiber, muscle, 74. 

Fibers of nerve, 217. 



Fibrillae, 74. 

Fibrin, 117, 129; ferment, 117. 

Fibula, 46. 

Filiform papilkp, 242. 

Fire, 284. 

Fish as food, 134. 

Fissures, 221. 

Fits, 287. 

Flavors, 243. 

Flexion, 52. 

Flies as vehicles of disease, 208. 

Floating ribs, 43. 

Focus, 22, 249. 

Follicle, 202. 

Food, 25 ; choice of, 91 ; classes of, 
89; definition of, 132; digestion 
of, 92 ; for use as energy, 28 ; for 
use as tissue, 25 ; in blood, 113, 
117; quantity of, necessary, 90, 
106 ; sources of, 25, 27 ; tests of, 
122 ; utilization of, in bodv, 30, 
90. 

Foods, heat energy in, 211 ; inor- 
ganic, 122, 135 ; iron content of, 
173 ; nutritive value of, 138, 139 ; 
organic, 88, 89, 122. 

Foot, 46. 

Foramen magnum, 50, 216. 

Foramina, 48. 

Foreign body, in ear, 286 ; in nose, 
286 ; in throat, 286. 

Formaldehyde (formalin), disin- 
fection (fumigation) by, 273. 

Fossa, 54. 

Fracture, 59, 285 ; healing of, 59. 

Freezing, effect of, upon meat, 
271 ; upon organized ferments, 
271, 275. 

Frontal bone, 47. 

Frostbites, 284. 

Fruits as food, 134. 

Fulcrum, 68. 

Fumigation, 273. 

Function, 31. 

Fungiform papillge, 242. 

Gall bladder, 102. 

Games, 294, 298. 

Ganglia, nerve, 158, 217 ; of heart, 

158. 
Ganglion cells, 217-219. 



314 



INDEX 



Gas exchange in respiration, 186, 
187. 

Gastric, digestion, 111, 125; 
glands, 94, 98. 

Gastric juice, 111; action of , 1 1 1, 1 25. 

Gills, 181. 

Gin, 148. 

Glands, 93; lymph (nodes), 166; 
racemose, 90 ; salivary, 93 ; se- 
baceous, 202 ; structure of, 94 ; 
sweat, 202. 

Globulin, 117. 

Glomeruli, 199. 

Glossoi)haryngeal nerve, 242. 

Glottis, 180. 

Glucose (dextrose, grape sugar), 
112; test for, 123. 

Gluten, 89. 

Glycerin, 112. 

Glycogen, 102, 115 ; in muscle, 78. 

Gout, 61. 

Grains, ]34. 

Grains (weight), 140. 

Grams, 140. 

Grape sugar. See Glucose. 

Gravel, 205. 

Gray matter, 218, 221. 

Growth, 18, 29. 

Gum, 109. 

Gutturals, 263. 

Gymnasium exercises, 293. 

Habits, 227. 

Hair, 201, 202. 

Hand, bones of, 45. 

Haversian, canals, 56; system, 56. 

Hay bacillus, 275. 

Head, 13, 47, 49. 

Headache, 206, 238, 270; medi- 
cines, 238. 

Health, 32. 

Hearing, 253. 

Heart, 14, 118, 154 ; action of, 158 ; 
beat, 159 ; muscle, 75, ] r)^ ; 
sounds, 159 
work of, 161. 

Heat, of body, 28, 209 ; elimination 
of, by skin, 203 ; elimination of, 
by lungs, 188 ; energy in foods, 
211 ; source of, 210. 

Hemispheres, cerebral, 220. 



Hemoglobin, 116, 173, 187. 

Hemorrhage, 172, 282. 

Hepatic, artery, 102; vein, 114: 
! duct, 102. 

Herbivora, 109. 
: Hilus, 198. 

Hinge joint, 52, 53. 

Hip, 45. 

Histological structure, 56. 

Home training, 228. 

Horny layer of skin, 201. 

Humerus, 45. 

Humor, aqueous, 245. 

Himger, sensation of, 239. 

Hydrochloric acid, 111, 125. 

Hydrogen, 20, 21. 

Hygiene, of circulatory system, 
170; of digestive organs, 103; of 
ar, 257 ; of excretory organs. 



204; of eye, 



of muscular 



system, 82; of nervous system, 
226; of nutrition, 132; of respi- 
ratory system, 189 ; of skeleton, 
58 ; of skin, 205 ; of the voice, 
263. 
Hysteria, 287. 

Ice water, 108. 

Ileocfecal valve, 102. 

Imbibition, 127. 

Immunity, 270, 280. 

Incisors, 95, 96. 

Incus, 255. 

Indestructibility of matter, 265. 

Indigestible elements of food, use 

for, 104, 138. 
Indigestion, 105, 108. 
Industrv, 228. 
Infection, 174, 268. 
Infectious diseases, 268-274, 280. 
Inferior, maxillary, 49; rectus, 

244: vena cava, 157. 
Inflammation, 106, 108, 270. 
Influenza, 279, 281. 
Infundibulum, 181. 
Ingestion, 92. 
Innominate, artery, 162; bone, 45; 

vein, 163. 
Inorganic, substances, 20, 21, 54. 
Insensible perspiration, 203. 
Insertion of muscle, 73. 



INDEX 



315 



Inspiration, 185. 

Instep, 46, 49. 

Insufflation, 285. 

Intelligence, 224. 

Intereelhilar substance, 15, 56. 

Intercostal muscles, external, 184 ; 
internal, 186. 

Internal ear, 255. 

Internal, oblique, 244 ; rectus, 244. 

Intervertebral, disk, 39 ; foramina, 
218. 

Intestinal, ferments, 111, 112; 
juice, 112. 

Intestine, large, 102 ; small, 100. 

Intestines, 93. 

Invertebrates, 50. 

Invert sugar, 112. 

Involuntary, action, 72, 225 ; mus- 
cle, 72, 75. 

Iodine test, 123. 

Iris, 245 ; muscle of, 245. 

Iron, 19, 21 ; in blood, 173 ; in food, 
173. 

Isolation, 279. 

Joint, 37, 53 ; ball and socket, 52 
capsule of, 51 ; diseases of, 60 
hinge, 53 ; immovable, 48, 51 
ligaments of, 51 ; movable, 37, 
51 ; structure of, 51. 

Joints, 37, 51, 85. 

Katabolism, 30. 
Kidueys, 14, 198-200. 
Kneecap, 46. 

Labials, 263. 

Labyrinth, membranous, of ear, 
255, 256. 

Lachrymal, bones, 49 ; ducts, 244 ; 
gland, 244. 

Lacteal, 101, 121. 

Lactose, 124. 

Lacunge, 56. 

Lamellae, 56. 

Large intestine, 102. 

Larynx, 180, 181, 261. 

Leg, skeleton of, 46. 

Lens, crystalline, 246 ; of micro- 
scope, 22. 

Lettuce, as food, 134. 



Leucocytes, 116, 167, 174, 177. 

Leucocytosis, 174. 

Lever, 68. 

Levers, classes of, 69. 

Lieberkiihn, crypts of, 100. 

Life, 24, 32. 

Ligament, suspensory, 246. 

Ligaments, 38, 57 ; of joint, 53, 57 ; 
of spine, 39. 

Light, 248. 

Limbs, 13. 

Lime, in body, 21, 137; in bone, 
54, 62 ; in food, 137. 

Litmus, 121. 

Liver, 93, 101, 113; action of, 114; 
structure of, 114. 

Lobules, 114. 

Localization in brain, 226. 

Long bone, 55. 

Long sight, 249. 

Lumbar vertebras, 39. 

Lungs, 14, 180 ; excretion by, 191. 

Lymph, 115, 118-120, 165, 166; 
nodes (glands), 166. 

Lymphatics, 113, 120, 165; struc- 
ture of, 166. 

Magnesium, 21. 

Malar bone, 48. 

Malleus, 255. 

Malpighian, capsule of kidney, 

199 ; layer, 201. 
Mammals, 50. 
Marrow, 55. 
Mastication, 96, 104. 
Matrix of nail, 204. 
Maxillar3% inferior, 49. 
Meals, 106, 140. 
Mealtime, 106. 
Measles, 269, 281. 
Meat, 91 ; as food, 134. 
Medulla, oblongata, 220 ; of bone, 

55 ; of kidney, 198. 
Medullary, cavity of bone, 55; 

portion of kidney, 198 ; sheath 

of nerve, 217. 
Medullated nerve fibers, 217. 
Membrane, mucous, 93 ; pleural, 

181; seroas, 155; synovial, 52. 
Membranous labyrinth, 255, 256. 
Meninges, 223 



316 



INDEX 



Mental training, 227. 

Mesentery, 100. 

Metabolism, 30 ; in brain, 225 ; in 
internal respiration, 188. 

Metacarpal, 45. 

Metatarsals, 46. 

Microscope, 22. 

Middle ear, 254, 255. 

Milk, 91 ; as food, 133 ; constitnents 
of, 124; Pasteurization of, 133; 
sterilization of, 133; tests for 
constituents of, 124. 

Mineral foods, 90, 135. 

Mineral salts, 90. 

Mineral substances, in body, 21, 
90 ; in food, 88, 123 ; in milk, 124 ; 
tests for, 123. 

Mitral valve, 156. 

Molar teeth, 95, 96. 

Molecule, 92, 112, 113, 124. 

Morphine, 237. 

Motion, 65 ; mechanism of, 68. 

Motor nerve, 218, 219. 

Mouth, 95, 179. 

Mucous membrane, 93 ; of stom- 
ach, 98. 

Mucus, 93. 

Mumps, 96. 

Muscle, chemical composition of. 
75 ; combustion in, 65, 68, 75 ; 
contraction of, 74 ; control of, 
68 ; glycogen in, 75 ; heart, 75, 
158 ; insertion of, 74 ; involun- 
tary, 72, 75 ; metabolism in, 68, 
75 ; nonstriate (involuntary), 72 ; 
origin of, 74 ; respiration in, 68, 
188 ; striate (voluntary), 72, 73 ; 
voluntary, 72, 73. 

Muscles, 13, 65 ; antagonistic, 66 ; 
diaphragm, the, 184; in rest, S5 ; 
in stomach, 98 ; intercostal, 184 ; 
in trachea, 182 ; in training, 82 ; 
list of, 76, 78 ; of arm, 67, 78 ; of 
eyeball, 244 ; of f a e e. 76 ; of hand , 
67, 78 ; of head, 76 ; of leg, 78 ; 
of neck, 76 ; of trunk, 76. 

Muscle sense, 258. 

Muscular exercise, 79, 81 ; in phys- 
ical culture, 293-300. 

Muscular system^ 65 ; hygiene of, 
79. 



Nails, 204. 

Nasal, bone, 49 ; duct, 244. 

Nephritis, '205. 277. 

Nerve, cell, 218, 219 ; ganglia, 217 ; 

structure of a, 217. 
Nerve fibers, 217; afferent, 216; 

efferent, 216; medullated, 217; 

motor, 218, 219 ; nonmedullated, 

217: sensory, 216, 219. 
Nerves, list of cranial, 222, 223; 

spinal, 218. 
Neryous system, 214. 
Neural arch, 39. 
Neurilemma, 217. 
Nicotine, 235. 
Nitrogeu, 21, 88, 91, 197. 
Nodes, Ivmph, 166 ; of nerve fiber. 

217. 
Nonmedullated nerve fiber, 217, 

224. 
Nose, 179, 180, 243. 
Nose bleed, 285. 
Nostrils, 243. 
Nucleolus, 17. 
Nucleus, 17. 
Nutrition, 87 ; hygiene of, 132. 

Obedience, habit of, 227. 

Observation, 228. 

Occipital bone, 47. 

Odontoid process, 41. 

Odor, 243. 

Oils, 90. 

Olfactory nerve, 222, 243. 

Opium, 237 ; habit, 237. 

Optic nerve, 222, 246. 

Organ, 31 ; of Corti, 256 ; of hear- 
ing, 254 ; of sight, 243 ; of taste, 
242. 

Organic substances, 20, 88, 122; 
as foods, 88, 122 ; in bone, 54, 62. 

Organized ferments, 111, 267. 

Organs, nerve, 214; of circulatiou. 
14, 154; of digestion, 14, 92; of 
excretion, 14, 197 ; of motion, 65 ; 
of respiration, 41, 179. 

Origin of muscle, 74. 

Osmosis, 120, 126; in intestinal 
absorption, 120. 

Ossification, 57, 58. 

Overeating, 105, 



INDEX 



317 



Overwork, 230. 

Oxidation, 28, 179; in mnsele, 65, 

75 ; in tissues, 188. 
Oxygen, 20, 21, 179 ; in blood, 187 ; 

in respiration, 187. 
Oxyhemoglobin, 116. 

Pain, 241. 
Palate, 49, 95. 
Pancreas, 93, 101, 102. 
Pancreatic, digestion, 112, 128 ; 

juice, 112. 
Papillae, of skin, 201 ; of tongue, 

242. 
Parasites, 33, 278. 
Parietal bone, 47. 
Parotid gland, 96. 
Pasteur cure for hydrophobia, 286. 
Pasteurization of milk, 133. 
Patella, 46. 

Patent medicines, 238. 
Peas, 134. 
Pectoral girdle, 44. 
Pelvic cavity, 45. 
Pelvic girdle, 44, 45. 
Pelvis of kidney, 198. 
Pepper, 141. 
Pepsin, 111, 125. 
Peptones, 111. 
Pericardium, 154. 
Perilymph, 256. 
Periosteum, 54. 
Peritoneum, 100. 
Permanent teeth, 96. 
Perspiration, 203. 
Peyer's patches, 101. 
Phagocytosis, 174. 
Phalanges, 45, 46. 
Pharynx, 93, 97, 180. 
Phenacetine, 238. 
Phosphates, 21; in blood, 117; in 

bone, 54, 62 ; test for, 62. 
Phosphorus, 21. 
Phthisis. See Consumption. 
Physical culture, 293. 
Physiologv, 31. 
Pia mate/, 223. 
Pitch, 257. 
Pivot joint, 41. 
Plain muscle. See Muscle, non- 

striate. 



Plants, metabolism in, 27 ; respira- 
tion of, 191 ; storage of energy 
in, 27. 

Plasma of blood, 115. 

Pleural membrane, 181, 182. 

Pneumogastric nerve, 223. 

Pneumonia. 277, 278 ; bacteria of, 
277, 281.' 

Poison, definition of a, 288. 

Poisoning, 289, 290. 

Pons, 220. 

Pores of skin, 202. 

Portal vein, 102, 113, 163. 

Posterior root of nerve, 219. 

Potassium, 21. 

Potatoes, 123; as food, 134. 

Precipitate, 122. 

Pressure, atmospheric, 185 ; blood, 
168 ; sense, 258. 

Prevention of disease, 207-209, 
277-292. 

Pronation, 53. 

Proteids, 21, 89 ; as food, 124 ; di- 
gestion of. 111, 124; in blood, 
117 ; tests for, 122. 

Protoplasm, composition of, 19. 

Psychic centers, 224. 

Ptomaines, 136. 

Ptyalin, 110. 

Pulmonary, artery, 165 ; circula- 
tion, 165 ; vein, 165. 

Pulp of teeth, 95. 

Pulse, 168. 

Pupil, 245, 246. 

Putrefaction, 136, 267. 

Pylorus, 99. 

Pvramids of kidney, 199. 

Pyridine, 236. 

Racemose glands, 94. 

Radius, 45. 

Reaction, chemical, 121 ; of muscle 
to stimulation, 85. 

Rectum, 103. 

Rectus, external, 244 ; internal, 244. 

Red corpuscle of blood, 115. 

Reduction of dislocation, 60. 

Reflex, act, 224 ; action, 224 ; cen- 
ters, 224. 

Refracting media, 248. 

Refraction, 248-250. 



318 



INDEX 



Regularity of bowels, 206. 

Regurgitation, 157. 

Relishes, 107. 

Reiinin, 111. 

Respiration, 179 ; artificial, 194, 
288 ; excretion by, 187, 188 ; ex- 
ternal, 179 ; in fishes, 181 ; inter- 
nal, 188; mechanism of, 183. 

Rest, muscular, 83 ; of brain, 230, 
231. 

Retina, 246. 

Rheumatism, 60, 277. 

Ribs, 41, 43 ; floating, 43. 

Rice, 134, 140. 

Rickets, 59. 

Rigor mortis, 75. 

Rods, 246. 

Roots, of hair, 202 ; of motor 
nerves, 219 ; of sensory nerves, 
219. 

Rotation, 52. 

Rum, 148. 

Running, 71. 

Saccharomyeetes, 144. 

Sacrum, 41. 

Saliva, 95, 96, 110 ; digestion by, 

110 ; reaction of, 121. 
Salivarv glands, 96. 
Salt (sodium chloride), 21, 90, 122, 

123 ; absorption of, 127 ; as food, 

135 ; reaction of, 121. 
Salt lick, 135. 
Sarcolemma, 74. 
Scalds, 284. 
Scapula, 44. 
Scarlet fever, 281.^ 
School seats, 59. 
Sclera, 245. 
Sclerosis, 175. 
Sebaceous glands, 202. 
Secretion, 94. 
Secretions, effect of alcohol upon, 

107 ; gastric, 111 ; intestinal, 102, 

112 ; of bacteria (ferments), 268 ; 

of liver, 101 ; salivary, 96. 
Self-control, 229. 
Semicircular canals, 256. 
Semilunar valves, 156, 157. 
Sensation, 239 ; center of, 224 ; of 

cold, 239; of fatigue, 239; of 



hunger, 239 ; of pain, 239, 241 ; 

of taste, 242 ; of touch, 240. 
Sensations, mental, 239. 
Sense organs, 240. 
Senses, special, 239 ; hearing, 253 ; 

muscular, 258 ; pressure, 258 ; 

sight, 243; smell, 243; taste, 

242 ; temperature, 241 ; touch, 

240. 
Sensible perspiration, 203. 
Sensory, nerve, 216, 219. 
Serous membrane, 155. 
Serum, 117, 128, 129. 
Shaft of bone, 54. 
Short sight, 249. 
Shoulder joint, 52. 
Sight, 243; long, 249; nerve of, 

222 ; organ of, 243 ; short, 249. 
Skeleton, 13, 37 ; of lower limbs, 

46 ; of upper limbs, 45. 
Skin, 13, 200 ; excretion by, 200. 
Skull, 47-49. 
Sleep, 230. 

Smallpox, 269, 271, 281 ; vaccina- 
tion against, 271, 280. 
Smell, 243 ; organ of, 243. 
Snake bite, 290. 
Soap, 112, 126. 
Soap baths, 206. 
Sodium, 21. 

Soluble substance, 121. 
Solution, 121. 
Sore throats, 190, 277. 
Sound, 253 ; transmission of, 257. 
Sounds, miisical, 257. 
Spasms, 287. 
Special senses, 239. 
Speech, 263. 
Sphenoid bone, 48. 
Sphincter muscle of eye, 251. 
Spinach, 134. 

Spinal, cord, 40, 216; nerves, 218. 
Spine, 38. 

Spinous process, 39. 
Spleen, 167. 
Spongy tissue, 55. 
Sport, athletic, 294, 298, 299. 
Sprains, 60, 284. 
Stapes, 255. 
Starch, 27, 110, 111, 123; tests for, 

123. 



INDEX 



319 



Steapsin, 112. 

Sterilize, 129, 133, 272. 

Sternum, 43. 

Stimulation of muscle, 85. 

Stomaeli, 14, 93, 98 ; glands of, 
94 ; membrane of, 98. 

Striate muscle, 74. 

Study, object of, 228. 

Subcutaneous tissue, 201. 

Sublingual glands, 96. 

Submaxillary glands, 96. 

Suffocation, 194, 288. 

Sugar, 27 ; cane, 112 ; grape (glu- 
cose), 112 ; invert, 112 ; tests, 
123. 

Sulphur, 21 ; disinfection by, 273. 

Sunstroke, 152, 287. 

Superior, oblique, 244 ; rectus, 244 ; 
vena cava, 157. 

Supination, 53. 

Suspensory ligament, 246. 

Sutures, 48. 

Swallowing, 98. 

Sweat, 202, 203 ; glands, 202. 

Sympathetic nervous system, 223. 

Synovial membrane, 52. 

Systole, 158. 

Tactile corpuscle, 240. 

Tarsals, 46. 

Tartar, 104. 

Taste, buds, 242; nerve of, 242; 

organ of, 242 ; sense of, 242. 
Tastes, 242. 
Tea, 142. 
Tears, 244. 
Teeth, 95; care of, 104; milk, 96; 

of earnivora and herbivora, 109 ; 

permanent, 96. 
Temperature, of body, 34, 209, 

210 ; regulation of, 210 ; sense of, 

241. 
Temporal, bone, 47 ; muscle, 76. 
Tendon of Achilles, 73. 
Tendons, 66, 73, 85. 
Thoracic, aorta, 162 ; duct, 166. 
Thorax, 41, 183. 
Tibia, 46. 
Tight lacing, 59. 
Tissue, 14 ; connective, 16, 58 ; 

epithelial, 16 ; muscular, 73, 75. 



Tissues, 11, 14; structure of, 15; 
varieties of, 15. 

Tobacco, 235 ; poisoning by, 237. 

Tobacco, effect of use of, upon ap- 
petite, 108 ; upon blood, 236 ; 
upon development, 236 ; upon 
digestion and digestive organs, 
108 ; upon heart, 176, 237 ; upon 
muscular development and 
strength, 84 ; upon nervous sys- 
tem, 236 ; upon respiratory 
organs. 189. 

Tongue, 95, 96, 241, 242. 

Tonsils, 193. 

Toothache, 288. 

Touch, 240. 

Toxines, 270. 

Trabeculee, 55. 

Trachea, 181, 182. 

Training, mental, 227 ; physical, 
82, 300. 

Transverse processes, 39. 

Triceps, 66, 78. 

Tricuspid valve, 157. 

Trunk, 13 ; skeleton of, 42. 

Trypsin, 111, 112; digestion by, 
128. 

Tuberculosis, 272, 273. 

Tubule of kidney, 199. 

Turbinate bones, 49, 243. 

Turmeric paper, 121. 

Tympanum, 254, 255. 

Typhoid fever, 208, 269. 

Ulna, 45. 
Uremia, 205. 
Urea, 114, 197, 200. 
Ureter, 198. 
Urine, 200. 
Uvula, 97. 

Vaccination, 271, 280. 

Vagus, 283. 

Valves, mitral, 156 ; of heart, 156, 
157 ; of veins, 169 ; semilunar, 
156, 157 ; trienspid, 157. 

Valvulse conniventes, 100. 

Varicose veins, 171. 

Vasomotor regulation of circula- 
tion, 169. 

Vegetables as food, 134. 



320 



INDEX 



Veins, 118, 161, 162; azygos, 163; 
hepatic, 165 ; inferior vena cava, 
163 ; innominate, 162, 163 ; jugu- 
lar, 163 ; of arm, 165 ; portal, 
163 ; pulmonary, 163 ; structure 
of, 162 ; subclavian, 163 ; supe- 
rior vena cava, 163. 

VensB cav£e, 157, 163. 

Venous blood, 119. 

Ventilation, 190, 191. 

Ventral cavity, 50. 

Ventricles of heart, 155, 156. 

Vertebra, 38, 39 ; body of, 39. 

Vertebrae, cervical, 38 ; dorsal, 38 ; 
lumbar, 39. 

Vertebrate, 50. 

Vestibule of ear, 256. 

Villi, 101, 113. 

Vitreous humor, 246. 

Vocal cords, 261, 262. 

Voice, 261 ; mechanism of, 262. 

Volition, 224. 

Voluntary acts, 224. 

Vomer, 49. 

Vomiting, to induce, 289. 



Walking, 71, 83. 

Waste, 197; disposal of, 207; 

elimination of, 103, 206. 
Water, as food, 135; composition 

of, 20 ; drinking, 105 ; in bone, 

63 ; in food, 90 ; in muscle, 85 ; 

reaction of, 121. 
Water, excretion of, by lungs, 

188 ; by kidneys, 200. 
Wax, 254. 
Wheat, 134. 
Whiskey, 148. 
White blood corpuscle, 115, 116^ 

172 ; amoeboid, 129. 
Whitelv Exerciser, 294. 
White matter (nerve), 218, 221. 
Windpipe (trachea), 181. 
Wine, 144, 145. 
Work of heart, 161. 
Wrist, 45. 

Xanthoproteic test forproteids, 122. 

Yeast, 144, 267, 274; fermentation 

by, 144, 274. 
Yellow spots, 247. 



JUL 21 1900 



